Systems and method for activating analyte sensor electronics

ABSTRACT

Various analyte sensor systems for controlling activation of analyte sensor electronics circuitry are provided. Related methods for controlling analyte sensor electronics circuitry are also provided. Various analyte sensor systems for monitoring an analyte in a host are also provided. Various circuits for controlling activation of an analyte sensor system are also provided. Analyte sensor systems utilizing a state machine having a plurality of states for collecting a plurality of digital counts and waking a controller responsive to a wake up signal are also provided. Related methods for such analyte sensor systems are also provided. Systems for controlling activation of analyte sensor electronics circuitry utilizing a magnetic sensor are further provided. One or more display device configured to display one or more analyte concentration values are also provided.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/400,873, filed May 1, 2019, which claims priority to U.S. ProvisionalApplication No. 62/666,554, filed May 3, 2018. The entire contents ofeach of the above-referenced patent applications are hereby incorporatedby reference.

TECHNICAL FIELD

The present developments relate generally to medical devices such asanalyte sensors, and more particularly, but not by way of limitation, tosystems, devices, and methods related to activating analyte sensorelectronics on such medical devices.

BACKGROUND

Diabetes mellitus is a disorder in which the pancreas cannot createsufficient insulin (Type I or insulin dependent) and/or in which insulinis not effective (Type 2 or non-insulin dependent). In the diabeticstate, the victim suffers from high blood sugar, which causes an arrayof physiological derangements (kidney failure, skin ulcers, or bleedinginto the vitreous of the eye) associated with the deterioration of smallblood vessels. A hypoglycemic reaction (low blood sugar) may be inducedby an inadvertent overdose of insulin, or after a normal dose of insulinor glucose-lowering agent accompanied by extraordinary exercise orinsufficient food intake.

Conventionally, a diabetic person carries a self-monitoring bloodglucose (SMBG) monitor, which may require uncomfortable finger prickingmethods. Due to the lack of comfort and convenience, a diabetic willnormally only measure his or her glucose level two to four times perday. Unfortunately, these time intervals are spread so far apart thatthe diabetic will likely be alerted to a hyperglycemic or hypoglycemiccondition too late, sometimes incurring dangerous side effects as aresult. In fact, it is not only unlikely that a diabetic will take atimely SMBG value, but will not know if his blood glucose value is goingup (higher) or down (lower), due to limitations of conventional methods.

Consequently, a variety of non-invasive, transdermal (e.g.,transcutaneous) and/or implantable electrochemical sensors are beingdeveloped for continuously detecting and/or quantifying blood glucosevalues. These devices generally transmit raw or minimally processed datafor subsequent analysis at a remote device, which can include a display.The transmission to wireless display devices can be wireless. The remotedevice can then provide the user with information about the user's bloodglucose levels. Because systems using such implantable sensors canprovide more up to date information to users, they may reduce the riskof a user failing to regulate the user's blood glucose levels.Nevertheless, such systems typically still rely on the user to takeaction in order to regulate the user's blood glucose levels, forexample, by making an injection.

Such systems may typically include a glucose sensor implantable into ahost and sensor electronics circuitry for processing and communicatingglucose related information. In such systems, however, the sensor andthe sensor electronics circuitry are usually designed to be connectedfor the first time by a user or host after the sensor has been implantedinto the user. Consequently, a pre-connected system can potentiallyreduce the amount of user interaction involved with deploying an analytesensor system.

This Background is provided to introduce a brief context for the Summaryand Detailed Description that follow. This Background is not intended tobe an aid in determining the scope of the claimed subject matter nor beviewed as limiting the claimed subject matter to implementations thatsolve any or all of the disadvantages or problems presented above.

SUMMARY

In view of the above characteristics associated with some systems, thereexists a need for an analyte sensor system in which an analyte sensorand analyte sensor electronics circuitry are configured to beelectrically and mechanically coupled to each other before the analytesensor is implanted into the user or host. The present disclosurerelates generally to controlling activation of sensor electronics forthe wireless communication of analyte data gathered using an analytesensor system. More particularly, the present disclosure is directed tosystems, methods, apparatuses, and devices, for using multipletechniques for controlling such activation in an analyte sensor systemin which the analyte sensor is connected both electrically andmechanically to analyte sensor electronics circuitry before the analytesensor is implanted in the host.

There are numerous advantages associated with the systems, methods,devices, and other aspects and embodiments of the present disclosure.For example, an analyte sensor system in which the analyte sensor isconfigured to be connected to the analyte sensor electronics circuitrybefore implantation may not need a lot of user interaction, and may besmaller, simpler, more elegant, and/or cheaper, and may have lesssealing, deployment, and connection issues. For example, analyte sensorconnection, alignment, and retention, and isolation issues related toanalyte sensor connection at the time of transcutaneous implantation maybe avoided. By way of further example, in systems not designed to bepre-connected, a seal may need to be made between the analyte sensorelectronics circuitry and the analyte sensor and/or housing thereof whenthe analyte sensor and the analyte sensor electronics circuitry arebrought together in the field. But, in a pre-connected system, thissealing can be accomplished during system manufacturing. Hence, faultsthat may occur as a result of analyte sensor insertion can be avoided.Another example advantage of the pre-connected system is that it may beadvantageous for the analyte sensor system to enter an active state tocapture analyte measurement values near the time the analyte sensor isimplanted into the user. This can enable an analyte processing algorithmto more accurately assess the time of sensor implantation and therebymore accurately process sensor signal analyte values.

There can also be a number of challenges associated with implementing apre-connected analyte sensor system. For example, in non-pre-connectedsystems, monitoring the analyte sensor electronics circuitry forelectrical signals indicative of an analyte sensor being present in thecircuit may be used to activate the analyte sensor system. But, in apre-connected system, such signals may be subject to noise, which maylead to false triggering/activation of the system. Additionally,monitoring of the analyte sensor prior to implantation may causeunwanted changes to the analyte sensor (e.g., deviation from calibrationvalues). Therefore, monitoring the analyte sensor electronics for onlyanalyte sensor signals may in certain instances not be well suited as aprimary or sole means for activation purposes.

Alternative and/or additional means of activating the analyte sensorsystem may thus be employed. Such means, however, should be robust tofalse wake-up events, should maintain accurate analyte sensorcalibration, should not consume significant power, and should enablesufficiently rapid wake-up of the analyte sensor system. Additionally,pre-connected systems should provide improved user experience, forexample, by reducing and/or eliminating user steps associated withconnection, and/or reducing and/or eliminating the possibility ofcombining incompatible sensors and electronics. Furthermore, and forexample, pre-connected systems and solutions may facilitate initiationof connections (e.g., wireless connections) faster in closed-loopsystems (e.g., automated insulin delivery systems and related or similarsystems and applications) that may lead to reduced gaps in the analytedata. Also, in a healthcare provider scenario (e.g., in a doctor's orother medical office) or the like, the amount of time involved withsetting up such systems (e.g., including time for sensor implantationinto a user's body and/or for activating or establishing operation ofanalyte sensor electronics) may be substantially reduced.

Embodiments of the present disclosure overcome these challenges andprovide the above described advantages by using multiple methods ofdetecting and confirming conditions for activating analyte sensorelectronics circuitry. By using one or more verification methods,embodiments of the present disclosure provide a system that is morerobust to false wake-ups, thus saving power and providing better overallreliability as well as providing the other advantages described above.To implement a robust wake-up or activation procedure and to avoid falsewake-up events, according to embodiments of the present disclosure,multiple indicators of analyte sensor insertion can be used to triggeranalyte sensor electronics circuitry to exit a lower power state. Inmany embodiments, the system is designed to largely avoid changing theproperties of the analyte sensor, to be robust to signal noise that maybe experienced prior to analyte sensor implantation (e.g., that mayresult from humidity, temperature, vibration, etc.), and to operate in amanner feasible for a low power battery-operated device.

In terms of the multiple techniques that may be used for detectingactivation events for the analyte sensor electronics circuitry, suchtechniques may generally be divided into those that utilize primarysignals and those that utilize secondary signals. As referred to herein,primary signals may generally relate to signals pertaining to,correlating to, derived from, characterizing, and/or describing analyteinformation as derived from a host who is using the analyte sensor. Asreferred to herein, secondary signals may generally relate toinformation gathered using the analyte sensor system, where the gatheredinformation is information other than the primary signal(s) (e.g., thegathered information is not information used in a primary signalcapacity to describe a relationship between the signal and the analyteinformation). Secondary signals or information may be gathered using theanalyte sensor (e.g., one or more electrodes) and/or other means. Suchother means may include circuits or components internal to the analytesensor system or external thereto, as described in further detailherein. Additionally, secondary signals or information may be gatheredusing the analyte sensor system and/or external components alone, or inconjunction with user interaction.

Combining multiple techniques that may be used for detecting activationevents for the analyte sensor electronics circuitry, for example, whereone technique can be used to check another technique that may be subjectto noise or false triggers, for example, where one or more primarysignal can be used to check one or more secondary signals, can increasesystem robustness to false wake ups. In some instances, a primary signal(e.g., analyte value or signal that may be representative thereof, suchas a voltage, current, count, or other signal) can be used incombination with a secondary signal that may be gathered/derived usingthe analyte sensor signal (e.g., analyte sensor impedance, capacitance,etc.). In some instances, the primary signal can be used in combinationwith one or more secondary signals that are not derived/gathered usingmeans other than or in addition to the analyte sensor. In embodiments,primary signal information can be combined with secondary signalinformation, which may be or include one or more non-analyte sensorsignals or information. In embodiments, the analyte sensor system canuse primary signal(s) and/or secondary signal(s) gathered/derived usingthe analyte sensor, and one or more signals or informationgathered/derived using means other than the analyte sensor (e.g., anaccelerometer signal or other technique as described herein) and cancompare the foregoing at one or more time periods for purposes ofactivating the analyte sensor system. In this manner, embodiments of thepresent disclosure can more accurately assess activation times, and/orbetter avoid and/or reduce false wake ups in a pre-connected analytesensor system, while maintaining a battery efficient lower power modeand robust sensor performance.

A first aspect of the present disclosure includes a system forcontrolling activation of analyte sensor electronics circuitry. Thesystem includes an analyte sensor that is electrically and mechanicallycoupled to analyte sensor electronics circuitry prior to transitioningthe system into an operational state. The analyte sensor electronicscircuitry is adapted to perform a number of operations. One suchoperation is to trigger an indication for the system to exit a lowerpower state and transition into the operational state. The indication istriggered based on a threshold value associated with deployment of thesystem. Another such operation is to, responsive to the indication,generate a control signal operable to cause the analyte sensor to gatherinformation related to a level of an analyte in a host. Yet another suchoperation is to generate a comparison between the information related tothe level of the analyte in the host and a condition. The system exitsthe lower power state and transitions into the operational mode based onthe indication being triggered and the comparison indicating that thelevel of the analyte in the host satisfies the condition.

In certain implementations of the first aspect, which may be generallyapplicable but are also particularly applicable in connection with anyother implementation of the first aspect, the analyte sensor electronicscircuitry is further adapted to cause the system to trigger theindication in response to the threshold value being satisfied for atleast a predetermined amount of time.

In certain implementations of the first aspect, which may be generallyapplicable but are also particularly applicable in connection with anyother implementation of the first aspect, the indication is a signalgenerated using one or more of an activation detection circuit and anactivation detection component that are adapted to detect one or more ofinsertion of the analyte sensor into the host and deployment of thesystem.

In certain implementations of the first aspect, which may be generallyapplicable but are also particularly applicable in connection with anyother implementation of the first aspect, the control signal is a signaloperable to cause a potentiostat to apply a voltage bias to the analytesensor and thereby cause the analyte sensor to gather the informationrelated to the level of the analyte in the host.

In certain implementations of the first aspect, which may be generallyapplicable but are also particularly applicable in connection with anyother implementation of the first aspect, after the system transitionsto the operational state, the system continues gathering the informationrelated to the level of the analyte in the host and communicates theinformation to one or more display devices or one or more partnerdevices.

In certain implementations of the first aspect, which may be generallyapplicable but are also particularly applicable in connection with anyother implementation of the first aspect, the threshold value is relatedto a level of a known analyte typically present in a human host.

In certain implementations of the first aspect, which may be generallyapplicable but are also particularly applicable in connection with anyother implementation of the first aspect, the indication is generatedusing one or more of (1) a detected proximity between the analyte sensorelectronics circuitry and a reference object; (2) a temperaturemonitored using the analyte sensor electronics circuitry; (3) an outputof an accelerometer of the analyte sensor electronics circuitry; (4) aresponse generated using wireless signaling transmitted or received bythe analyte sensor electronics; (5) a detected change in air pressuremeasured by the analyte sensor electronics circuitry; (6) audioinformation monitored by the analyte sensor electronics circuitry; (7) asignal generated by the analyte sensor electronics circuitry in responseto photons detected by the analyte sensor electronics circuitry; (8) aconductivity measured between two terminals of the analyte sensorelectronics circuitry; (9) a mechanical switch located on or within ahousing of the analyte sensor electronics circuitry; (10) a componentadapted to change a connection between two conductive elements of theanalyte sensor electronics circuitry, in response to movement of thecomponent; and (11) a measured strain.

In certain implementations of the first aspect, which may be generallyapplicable but are also particularly applicable in connection with anyother implementation of the first aspect, the system exits the lowerpower state based on the determination that the level of analyte in ahost exceeds a threshold value.

In certain implementations of the first aspect, which may be generallyapplicable but are also particularly applicable in connection with anyother implementation of the first aspect, the analyte sensor electronicscircuitry is further adapted to cause the system to trigger theindication in response to a condition being satisfied for programmedintervals of time.

In certain implementations of the first aspect, which may be generallyapplicable but are also particularly applicable in connection with anyother implementation of the first aspect, the information related to thelevel of the analyte in the host is used to generate detected counts.Further, the condition includes a threshold characteristic for thecounts. If the comparison indicates that the detected counts meet thethreshold, the system exits the lower power state and enters theoperational mode.

A second aspect of the present disclosure includes a method forcontrolling analyte sensor electronics circuitry. The method includesthe analyte sensor electronics circuitry obtaining a first signalgenerated using one or more of an analyte sensor and a secondary sensor.The method further includes determining whether a first condition is metbased on the first signal obtained by the analyte sensor electronicscircuitry. The method also includes, responsive to the first conditionbeing met, the analyte sensor electronics circuitry activating ananalyte measurement circuit. Additionally, the method includes theanalyte measurement circuit using the analyte sensor to gatherinformation related to an analyte value in a host. The analyte sensorwas coupled to the analyte sensor electronics before the analyte sensorwas implanted into the host. The method also includes the analyte sensorelectronics circuitry determining whether the information related to theanalyte value in the host meets a second condition.

Additionally, the method according to the second aspect includes,responsive to the analyte sensor electronics circuitry determining thatthe information related to the analyte value in the host meets thesecond condition, the sensor electronics circuitry exiting the lowerpower consumption mode. Alternatively, the method includes, responsiveto the analyte sensor electronics circuitry determining that theinformation related to the analyte value in the host does not meet thesecond condition, the analyte sensor electronics circuitry remaining inthe lower power consumption mode and obtaining a second electricalsignal that indicates whether the first condition has been met.

In certain implementations of the second aspect, which may be generallyapplicable but are also particularly applicable in connection with anyother implementation of the second aspect, the second condition is metif the information related to the analyte value indicates that the levelof the analyte value in the host satisfies a threshold value.

In certain implementations of the second aspect, which may be generallyapplicable but are also particularly applicable in connection with anyother implementation of the second aspect, the first conditionrepresents a proximity of the analyte sensor electronics circuitry to areference point.

In certain implementations of the second aspect, which may be generallyapplicable but are also particularly applicable in connection with anyother implementation of the second aspect, the first conditionrepresents a level of acceleration detected using an accelerometer.

In certain implementations of the second aspect, which may be generallyapplicable but are also particularly applicable in connection with anyother implementation of the second aspect, the first condition relatesto one or more electrical characteristics measured for the analytesensor.

A third aspect of the present disclosure includes a system formonitoring an analyte in a host. The system includes an analyte sensor.The analyte sensor includes one or more electrodes that are adapted togather information related to a level of the analyte in the host. Thesystem also includes sensor electronics circuitry mechanically andelectrically coupled to the analyte sensor before the analyte sensor isimplanted into the host. The sensor electronics circuitry is adapted togenerate a secondary indicator using a first condition and a measurementof an electrical signal passed between at least two of the one or moreelectrodes. The sensor electronics circuitry is further adapted to causethe system to enter the active state in response to the sensorelectronics circuitry generating a confirmation of the secondaryindicator using a second condition and the information related to thelevel of the analyte in the host.

In certain implementations of the third aspect, which may be generallyapplicable but are also particularly applicable in connection with anyother implementation of the third aspect, the sensor electronicscircuitry is further adapted to use the measurement of the electricalsignal passed between the at least two of the one or more electrodes todetermine one or more of an impedance, capacitance, voltage, and currentassociated with the one or more electrodes.

A fourth aspect of the present disclosure includes a system formonitoring an analyte in a host. The system includes analyte sensorelectronics circuitry. The system further includes an analyte sensorthat is mechanically and electrically coupled to the analyte sensorelectronics circuitry before the analyte sensor is implanted into thehost. In addition, the system includes an activation detection circuitcoupled to the analyte sensor. The activation detection circuit isadapted to generate a control signal operable to cause the analytesensor to obtain information related to a level of the analyte in thehost. The control signal is generated in response to an electricalsignal indicating that a first condition is satisfied. The analytesensor electronics circuitry is adapted to cause the system to changestates if the level of the analyte in the host satisfies a secondcondition and if the electrical signal indicates that the firstcondition is satisfied.

In certain implementations of the fourth aspect, which may be generallyapplicable but are also particularly applicable in connection with anyother implementation of the fourth aspect, the indication that the firstcondition is satisfied is generated using one or more of parameters,inputs, and/or variables. For example, any of the following, alone or incombination, may be used for generating the indication. The indicationmay be generated using a detected proximity between the analyte sensorelectronics circuitry and a reference object. The indication may begenerated using a temperature monitored by the analyte sensorelectronics circuitry. The indication may be generated using an outputof an accelerometer of the analyte sensor electronics circuitry. Inembodiments, the indication may be generated using a response generatedusing wireless signaling transmitted or received by the analyte sensorelectronics. Further, the indication may be generated using a detectedchange in air pressure measured by the analyte sensor electronicscircuitry. Audio information that can be monitored by the analyte sensorelectronics circuitry may also be used to generate the indication.Additionally, the indication may be generated using a signal generatedby the analyte sensor electronics circuitry in response to photonsdetected by the analyte sensor electronics circuitry. A conductivitymeasured between two terminals of the analyte sensor electronicscircuitry may also be used to generate the indication. In some cases,the indication may be generated using a mechanical switch located on orwithin a housing of the analyte sensor electronics circuitry. Inembodiments, the indication may be generated using a component adaptedto change a connection between two conductive elements of the analytesensor electronics circuitry, in response to movement of the component.The indication can be generated using a measured strain.

A fifth aspect of the present disclosure includes a system formonitoring an analyte in a host. The system includes analyte sensorelectronics circuitry. The system further includes an analyte sensoradapted to be coupled to the analyte sensor electronics circuitry beforethe analyte sensor is implanted into the host. Additionally, the systemincludes an activation detection circuit coupled to the analyte sensor.The activation detection circuit is adapted to monitor a secondarysensor according to a sampling frequency and to increase the samplingfrequency in response to a first event detected using the secondarysensor. The activation detection circuit is further adapted to monitorthe secondary sensor according to the increased sampling frequency andto generate a control signal in response to detecting a second event.The control signal is operable to cause the analyte sensor to make ameasurement for obtaining information indicative of a level of theanalyte in the host when the analyte sensor is implanted in the host.The analyte sensor electronics circuitry is further adapted to cause thesystem to change states in response to the information indicative of thelevel of the analyte in the host satisfying a condition, and further inresponse to the activation detection circuit detecting the second event.

In certain implementations of the fifth aspect, which may be generallyapplicable but are also particularly applicable in connection with anyother implementation of the fifth aspect, the sampling frequency is setaccording to a classification of one or more of the first event and thesecond event as determined by an activation detection component.

A sixth aspect of the present disclosure includes a circuit forcontrolling activation of an analyte sensor system. The circuit includesa detection circuit adapted to indicate whether a signal at an inputterminal of the detection circuit meets a condition. The detectioncircuit is further adapted to trigger the analyte system to exit a lowerpower state if the detection circuit indicates that the signal meets thecondition. The circuit also include a first switch element adapted tocontrol a coupling between the input terminal of the detection circuitand a first terminal of an analyte sensor. The analyte sensor is adaptedto gather information related to an analyte level in a host. The circuitfurther includes a second switch element adapted to control a couplingbetween the first terminal of the analyte sensor and a first terminal ofa potentiostat. The potentiostat is adapted to apply a voltage bias tothe analyte sensor that causes the analyte sensor to gather theinformation related to the level of the analyte in the host. The inputterminal of the detection circuit is coupled to a second terminal of theanalyte sensor and to a second terminal of the potentiostat. The circuitis adapted to generate additional detectable events for activating theanalyte sensor system, including by, at a first time, causing the secondswitch element to couple the first terminal of the analyte sensor to thefirst terminal of the potentiostat and the first switch element todecouple the input terminal of the detection circuit from the firstterminal of the analyte sensor. At a second time, the circuit is adaptedto cause the second switch element to decouple the first terminal of theanalyte sensor from the first terminal of the potentiostat and the firstswitch element to couple the input terminal of the detection circuit tothe first terminal of the analyte sensor.

In certain implementations of the sixth aspect, which may be generallyapplicable but are also particularly applicable in connection with anyother implementation of the sixth aspect, the circuit also includes acapacitive element coupled between the input terminal of the detectioncircuit and a second reference voltage.

In certain implementations of the sixth aspect, which may be generallyapplicable but are also particularly applicable in connection with anyother implementation of the sixth aspect, the second switch element isadapted to couple the input terminal of the detection circuit to thefirst terminal of the analyte sensor through a resistive element.

In certain implementations of the sixth aspect, which may be generallyapplicable but are also particularly applicable in connection with anyother implementation of the sixth aspect, the circuit further includes athird switch element adapted to couple the input terminal of thedetection circuit to the second reference voltage.

In certain implementations of the sixth aspect, which may be generallyapplicable but are also particularly applicable in connection with anyother implementation of the sixth aspect, when the third switch elementcouples the input terminal of the detection circuit to the secondreference voltage, the capacitive element is discharged.

In certain implementations of the sixth aspect, which may be generallyapplicable but are also particularly applicable in connection with anyother implementation of the sixth aspect, a terminal of the third switchelement is coupled to a clock that causes the third switch element toperiodically couple the input terminal of the detection circuit to thesecond reference voltage.

In certain implementations of the sixth aspect, which may be generallyapplicable but are also particularly applicable in connection with anyother implementation of the sixth aspect, the first switch element isdriven by a common signal and the second switch element is driven by aninverted version of the common signal.

In certain implementations of the sixth aspect, which may be generallyapplicable but are also particularly applicable in connection with anyother implementation of the sixth aspect, the first switch element andthe second switch element are driven by a common signal and haveopposite polarities.

In certain implementations of the sixth aspect, which may be generallyapplicable but are also particularly applicable in connection with anyother implementation of the sixth aspect, a voltage at the inputterminal of the detection circuit is indicative of a current between thefirst terminal of the analyte sensor and the second terminal of theanalyte sensor when the analyte sensor is implanted in a host.

In certain implementations of the sixth aspect, which may be generallyapplicable but are also particularly applicable in connection with anyother implementation of the sixth aspect, a reference terminal of thedetection circuit is coupled to a first reference voltage. The detectioncircuit includes a comparator.

In certain implementations of the sixth aspect, which may be generallyapplicable but are also particularly applicable in connection with anyother implementation of the sixth aspect, the second voltage referenceis ground.

In some embodiments, an analyte sensor system is provided. The analytesensor system includes an analyte sensor. The analyte sensor systemincludes a state machine configured to cause a first voltage potentialto be applied across the analyte sensor during a first sampling stateand cause a second voltage potential to be applied across the analytesensor during a second sampling state. The analyte sensor systemincludes analyte sensor measurement circuitry configured to generate afirst digital count corresponding to a first current flowing through theanalyte sensor during the first sampling state based on application ofthe first voltage potential and generate a second digital countcorresponding to a second current flowing through the analyte sensorduring the second sampling state based on application of the secondvoltage potential. The analyte sensor system includes detectioncircuitry configured to determine a first difference between the seconddigital count and the first digital count and generate a controller wakeup signal responsive to at least the first difference satisfying athreshold value. The analyte sensor system includes a controllerconfigured to enter a lower power state for at least a duration of thefirst sampling state, the second sampling state and the determination ofthe first difference and to transition from the lower power state to anoperational state responsive to the controller wake up signal. Thecontroller is configured to determine an impedance of the analyte sensorbased at least in part on the first difference.

In some embodiments, the state machine is configured to cause initiationof the first voltage potential applied across the analyte sensor duringa first delay state that immediately precedes the first sample state,and the analyte sensor measurement circuitry is configured to suspendgeneration of digital counts during the first delay state.

In some embodiments, the state machine is configured to cause initiationof the second voltage potential applied across the analyte sensor duringa second delay state that immediately precedes the second sample state,and the analyte sensor circuitry is configured to suspend generation ofdigital counts during the second delay state.

In some embodiments, the state machine is configured to cause azero-voltage potential to be applied across the analyte sensor during athird delay state that follows the second sampling state, and theanalyte sensor measurement circuitry is configured to suspend generationof digital counts during the third delay state.

In some embodiments, the detection circuitry includes a first samplebuffer configured to store the first digital count. In some embodiments,the detection circuitry includes a differentiator configured to receivethe first digital count from the first sample buffer, receive the seconddigital count from the analyte sensor measurement circuitry, anddetermine the first difference.

In some embodiments, the detection circuitry includes an accumulatorconfigured to generate a sum of the first difference and at least asecond difference between a third digital count and a fourth digitalcount. The third digital count corresponds to a third current flowingthrough the analyte sensor during a subsequent instance of the firstsampling state and the fourth digital count corresponds to a fourthcurrent flowing through the analyte sensor during a subsequent instanceof the second sampling state. In some embodiments, the detectioncircuitry is configured to generate the controller wake up signalresponsive to at least the sum of the first difference and the seconddifference satisfying the threshold value.

In some embodiments, the controller is configured to define at least oneparameter of the state machine before entering the lower power state. Insome embodiments, in a first operating mode of the analyte sensorsystem, the first voltage potential is zero volts and the second voltagepotential is greater than the first voltage potential by a predeterminedamount, and in a second operating mode of the analyte sensor system, thefirst voltage potential is the same as a voltage potential appliedacross the analyte sensor to determine analyte concentrations within thehost and the second voltage potential is greater than the first voltagepotential by the predetermined amount.

In some embodiments, a method for controlling an analyte sensor systemis provided. The method includes utilizing a state machine to cause afirst voltage potential to be applied across an analyte sensor during afirst sampling state and cause a second voltage potential to be appliedacross the analyte sensor during a second sampling state. The methodincludes utilizing analyte sensor measurement circuitry to generate afirst digital count corresponding to a first current flowing through theanalyte sensor during the first sampling state based on application ofthe first voltage potential and generate a second digital countcorresponding to a second current flowing through the analyte sensorduring the second sampling state based on application of the secondvoltage potential. The method includes utilizing detection circuitry todetermine a first difference between the second digital count and thefirst digital count, and generate a controller wake up signal responsiveto at least the first difference satisfying a threshold value. Themethod includes causing a controller to enter a lower power state for atleast a duration of the first sampling state, the second sampling stateand the determination of the first difference, transition from the lowerpower state to an operational state responsive to the controller wake upsignal and determine an impedance of the analyte sensor based at leastin part on the first difference.

In some embodiments, the method includes initiating application of thefirst voltage potential across the analyte sensor during a first delaystate that immediately precedes the first sample state and suspendinggeneration of digital counts by the analyte sensor measurement circuitryduring the first delay state.

In some embodiments, the method includes initiating application of thesecond voltage potential across the analyte sensor during a second delaystate that immediately precedes the second sample state and suspendinggeneration of digital counts by the analyte sensor measurement circuitryduring the second delay state.

In some embodiments, the method includes utilizing the state machine tocause a zero-voltage potential to be applied across the analyte sensorduring a third delay state that follows the second sample state andsuspending generation of digital counts by the analyte sensormeasurement circuitry during the third delay state.

In some embodiments, the method includes storing the first digital countin a first sample buffer prior to determining the first difference. Insome embodiments, the method includes receiving, by a differentiator,the first digital count from the first sample buffer, receiving, by thedifferentiator, the second digital count from the analyte sensormeasurement circuitry, and utilizing the differentiator to determine thefirst difference.

In some embodiments, the method includes utilizing an accumulator togenerate a sum of the first difference and at least a second differencebetween a third digital count and a fourth digital count, the thirddigital count corresponding to a third current flowing through theanalyte sensor during a subsequent instance of the first sampling stateand the fourth digital count corresponding to a fourth current flowingthrough the analyte sensor during a subsequent instance of the secondsampling state.

In some embodiments, the method includes generating the controller wakeup signal responsive to at least the sum of the first difference and thesecond difference satisfying the threshold value.

In some embodiments, the method includes utilizing the controller todefine at least one parameter of the state machine before entering thelower power state.

In some embodiments, in a first operating mode of the analyte sensorsystem, the first voltage potential is zero volts and the second voltagepotential is greater than the first voltage potential by a predeterminedamount and, in a second operating mode of the analyte sensor system, thefirst voltage potential is the same as a voltage potential appliedacross the analyte sensor to determine analyte concentrations within thehost and the second voltage potential is greater than the first voltagepotential by the predetermined amount.

In some embodiments, a system for controlling activation of analytesensor electronics circuitry is provided. The system includes an analytesensor, a magnetic sensor configured to trigger a wake signal responsiveto a magnet being brought sufficiently close to the magnetic sensor, andanalyte sensor electronics circuitry configured to exit a lower powerstate and transition into an operational state responsive to the wakesignal and, responsive to transitioning into the operational state,receive an indication of one or more analyte concentration values fromthe analyte sensor.

In some embodiments, the magnet is disposed on a display deviceconfigured to display the one or more analyte concentration values. Insome embodiments, the magnetic sensor is configured to trigger the wakesignal responsive to the magnet being moved in at least one of apredetermined motion and a predetermined spatial orientation withrespect to the magnetic sensor.

In some embodiments, a display device configured to display one or moreanalyte concentration values is provided. The display device includes amicrophone configured to generate one or more audio waveforms of a soundmade by an applicator while deploying the analyte sensor system. Thedisplay device includes a processor configured to execute an applicationwhile the applicator is deploying the analyte sensor system. Theapplication is configured to analyze the one or more audio waveforms andidentify one of a successful deployment and an unsuccessful deploymentof the analyte sensor system based on the analyzing the one or moreaudio waveforms. The display device includes a display configured todisplay at least one of a first indication of a successful deploymentresponsive to the application identifying the successful deployment anda second indication of an unsuccessful deployment responsive to theapplication identifying the unsuccessful deployment.

In some embodiments, the analyzing the one or more audio waveformsincludes identifying at least one portion of the one or more audiowaveforms indicative of at least one part of the applicator performing aknown movement of the successful deployment.

This summary is intended to provide an overview of subject matter of thepresent patent application. It is not intended to provide an exclusiveor exhaustive explanation of the disclosure. The detailed description isincluded to provide further information about the present patentapplication. Other aspects of the disclosure will be apparent to personsskilled in the art upon reading and understanding the following detaileddescription and viewing the drawings that form a part thereof, each ofwhich are not to be taken in a limiting sense.

BRIEF DESCRIPTION OF THE DRAWINGS

Further aspects of the present disclosure will be more readilyappreciated upon review of the detailed description of the variousdisclosed embodiments, described below, when taken in conjunction withthe accompanying figures.

FIG. 1 illustrates aspects of an example system that may be used inconnection with some embodiments;

FIG. 2 illustrates aspects of an example system that may be used inconnection with some embodiments;

FIG. 3A is an example analyte sensor system, in accordance with someembodiments;

FIG. 3B is an example analyte sensor system, in accordance with someembodiments;

FIG. 4 illustrates aspects of an example analyte sensor system, inaccordance with some embodiments;

FIG. 5 illustrates aspects of an example analyte sensor system, inaccordance with some embodiments;

FIG. 6A illustrates aspects of an example application apparatus, inaccordance with some embodiments;

FIG. 6B illustrates another view of an example application apparatus, inaccordance with some embodiments;

FIG. 6C illustrates aspects of an example activation detectioncomponent, in accordance with some embodiments;

FIG. 6D illustrates aspects of a top view of an example connector, inaccordance with some embodiments;

FIG. 6E illustrates aspects of a top view of another example connector,in accordance with some embodiments;

FIG. 7A illustrates an example circuit diagram of an analyte sensor, inaccordance with some embodiments;

FIG. 7B illustrates an example plot of analyte sensor impedance as afunction of time, in accordance with some embodiments;

FIG. 7C illustrates an example plot of analyte sensor impedance as afunction of time, in accordance with some embodiments;

FIG. 8A illustrates aspects of an example activation detection circuit,in accordance with some embodiments;

FIG. 8B illustrates an example plot of an analyte sensor signal, inaccordance with some embodiments;

FIG. 8C is an operational flow diagram illustrating various operationsthat may be performed, in accordance with some embodiments;

FIG. 9 illustrates example plots illustrating the operation of anexample analyte sensor system, in accordance with some embodiments;

FIG. 10 is an operational flow diagram illustrating various operationsthat may be performed, in accordance with some embodiments;

FIG. 11 illustrates an example computing module, in accordance with someembodiments;

FIG. 12 illustrates a timing diagram related to a state-machine forultimately determining an impedance of an analyte sensor, in accordancewith some embodiments;

FIG. 13 illustrates a state diagram related to a state-machine forultimately determining an impedance of an analyte sensor, in accordancewith some embodiments;

FIG. 14 illustrates a functional block diagram related to astate-machine for ultimately determining an impedance of an analytesensor, in accordance with some embodiments; and

FIG. 15 illustrates a flowchart for a method of controlling an analytesensor system, in accordance with some embodiments.

The figures are described in greater detail in the description andexamples below, are provided for purposes of illustration only, andmerely depict typical or example embodiments of the disclosure. Thefigures are not intended to be exhaustive or to limit the disclosure tothe precise form disclosed. It should also be understood that thedisclosure may be practiced with modification or alteration, and thatthe disclosure may be limited only by the claims and the equivalentsthereof.

DETAILED DESCRIPTION

Embodiments of the present disclosure are directed to systems, methods,and devices for wireless communication of analyte data. In variousdeployments described herein, the analyte data is glucose data generatedby an analyte sensor system configured to connect to display devices,partner devices (e.g., medical devices such as an insulin pump), otherremote connectable devices, and the like. Implementing aspects of thepresent disclosure, including more particularly, the systems, methods,apparatuses, and devices described herein that provide increasedrobustness against false or otherwise undesired activation, wakeups,and/or related mode or state changes, or the like, for components of ananalyte sensor system, may improve the accuracy, robustness, and/orpower management of the analyte sensor system in wireless communicationswith a display device, one or more partner devices, and/or other (e.g.,electronic) devices. Moreover, implementing aspects of the presentdisclosure may also allow for improving performance with respect tolongevity and usability of the analyte sensor system.

The details of some example embodiments of the systems, methods, anddevices of the present disclosure are set forth in this description andin some cases, in other portions of the disclosure. Other features,objects, and advantages of the disclosure will be apparent to one ofskill in the art upon examination of the present disclosure,description, figures, examples, and claims. It is intended that all suchadditional systems, methods, devices, features, and advantages beincluded within this description (whether explicitly or by reference),be within the scope of the present disclosure, and be protected by oneor more of the accompanying claims.

System Overview & Example Configurations

FIG. 1 depicts system 100 that may be used in connection withembodiments of the present disclosure that involve gathering,monitoring, and/or providing information regarding analyte valuespresent in a user's body, including for example the user's blood glucosevalues. System 100 depicts aspects of analyte sensor system 8 that maybe communicatively coupled to display devices 110, 120, 130, and 140,partner devices 136, and/or server system 134.

Analyte sensor system 8 in the illustrated embodiment includes analytesensor electronics module 12 and analyte sensor 10 associated withanalyte sensor electronics module 12. Analyte sensor electronics module12 may be electrically and mechanically coupled to analyte sensor 10before analyte sensor 10 is implanted in a user or host. Accordingly,analyte sensor 10 may not require a user to couple analyte sensorelectronics module 12 to analyte sensor 10. For example, analyte sensorelectronics module 12 may be physically/mechanically and electricallycoupled to analyte sensor 10 during manufacturing, and thisphysical/mechanical and electrical connection may be maintained duringshipping, storage, insertion, use, and removal of analyte sensor system8. As such, the electro-mechanically connected components (e.g., analytesensor 10 and analyte sensor electronics module 12) of analyte sensorsystem 8 may be referred to as a “pre-connected” system. Analyte sensorelectronics module 12 may be in wireless communication (e.g., directlyor indirectly) with one or more of display devices 110, 120, 130, and140. In addition, or alternatively to display devices 110, 120, 130, and140, analyte sensor electronics module 12 may be in wirelesscommunication (e.g., directly or indirectly) with partner devices 136and/or server system 134. Likewise, in some examples, display devices110-140 may additionally or alternatively be in wireless communication(e.g., directly or indirectly) with partner devices 136 and/or serversystem 134. Various couplings shown in FIG. 1 can be facilitated withwireless access point 138, as also mentioned below.

In certain embodiments, analyte sensor electronics module 12 includeselectronic circuitry associated with measuring and processing analytesensor data or information, including prospective algorithms associatedwith processing and/or calibration of the analyte sensordata/information. Analyte sensor electronics module 12 can bephysically/mechanically connected to analyte sensor 10 and can beintegral with (non-releasably attached to) or releasably attachable toanalyte sensor 10. Analyte sensor electronics module 12 may also beelectrically coupled to analyte sensor 10, such that the components maybe electromechanically coupled to one another. Analyte sensorelectronics module 12 may include hardware, firmware, and/or softwarethat enables measurement and/or estimation of levels of the analyte in ahost/user via analyte sensor 10 (e.g., which may be/include a glucosesensor). For example, analyte sensor electronics module 12 can includeone or more of a potentiostat, a power source for providing power toanalyte sensor 10, other components useful for signal processing anddata storage, and a telemetry module for transmitting data from thesensor electronics module to one or more display devices. Electronicscan be affixed to a printed circuit board (PCB) within analyte sensorsystem 8, or platform or the like, and can take a variety of forms. Forexample, the electronics can take the form of an integrated circuit(IC), such as an Application-Specific Integrated Circuit (ASIC), amicrocontroller, a processor, and/or a state machine.

Analyte sensor electronics module 12 may include sensor electronics thatare configured to process sensor information, such as sensor data, andgenerate transformed sensor data and displayable sensor information.Examples of systems and methods for processing sensor analyte data aredescribed in more detail herein and in U.S. Pat. Nos. 7,310,544 and6,931,327 and U.S. Patent Publication Nos. 2005/0043598, 2007/0032706,2007/0016381, 2008/0033254, 2005/0203360, 2005/0154271, 2005/0192557,2006/0222566, 2007/0203966 and 2007/0208245, all of which areincorporated herein by reference in their entireties.

With further reference to FIG. 1, display devices 110, 120, 130, and/or140 can be configured for displaying (and/or alarming) displayablesensor information that may be transmitted by sensor electronics module12 (e.g., in a customized data package that is transmitted to thedisplay devices based on their respective preferences). Each of displaydevices 110, 120, 130, or 140 can (respectively) include a display suchas touchscreen display 112, 122, 132, /or 142 for displaying sensorinformation and/or analyte data to a user and/or receiving inputs fromthe user. For example, a graphical user interface (GUI) may be presentedto the user for such purposes. In embodiments, the display devices mayinclude other types of user interfaces such as voice user interfaceinstead of or in addition to a touchscreen display for communicatingsensor information to the user of the display device and/or receivinguser inputs. In embodiments, one, some, or all of display devices 110,120, 130, 140 may be configured to display or otherwise communicate thesensor information as it is communicated from sensor electronics module12 (e.g., in a data package that is transmitted to respective displaydevices), without any additional prospective processing required forcalibration and/or real-time display of the sensor data.

The plurality of display devices 110, 120, 130, 140 depicted in FIG. 1may include a custom display device, for example, analyte display device110, specially designed for displaying certain types of displayablesensor information associated with analyte data received from sensorelectronics module 12 (e.g., a numerical value and/or an arrow, inembodiments). In embodiments, one of the plurality of display devices110, 120, 130, 140 includes a smartphone, such as mobile phone 120,based on an Android, iOS, or other operating system, and configured todisplay a graphical representation of the continuous sensor data (e.g.,including current and/or historic data).

As further illustrated in FIG. 1 and mentioned above, system 100 mayalso include wireless access point (WAP) 138 that may be used to coupleone or more of analyte sensor system 8, the plurality display devices110, 120, 130, 140 etc., server system 134, and medical device 136 toone another. For example, WAP 138 may provide WiFi and/or cellular orother wireless connectivity within system 100. Near Field Communication(NFC) may also be used among devices of system 100 for exchanging data,as well as for performing specialized functions, e.g., waking up orpowering a device or causing the device (e.g., analyte sensorelectronics module 12 and/or a transmitter) to exit a lower power modeor otherwise change states and/or enter an operational mode. Serversystem 134 may be used to collect analyte data from analyte sensorsystem 8 and/or the plurality of display devices, for example, toperform analytics thereon, generate universal or individualized modelsfor glucose levels and profiles, provide services or feedback, includingfrom individuals or systems remotely monitoring the analyte data, and soon. Partner device(s) 136, by way of overview and example, can usuallycommunicate (e.g., wirelessly) with analyte sensor system 8, includingfor authentication of partner device(s) 136 and/or analyte sensor system8, as well as for the exchange of analyte data, medicament data, otherdata, and/or control signaling or the like. Partner devices 136 mayinclude a passive device in example embodiments of the disclosure. Oneexample of partner device 136 may be an insulin pump for administeringinsulin to a user in response and/or according to an analyte level ofthe user as measured/approximated using analyte sensor system 8. For avariety of reasons, it may be desirable for such an insulin pump toreceive and track glucose values transmitted from analyte sensor system8 (with reference to FIG. 1 for example). One example reason for this isto provide the insulin pump a capability to suspend/activate/controlinsulin administration to the user based on the user's glucose valuebeing below/above a threshold value.

Referring now to FIG. 2, system 200 is depicted. System 200 may be usedin connection with implementing embodiments of the disclosed systems,methods, apparatuses, and/or devices, including, for example, aspectsdescribed above in connection with FIG. 1. By way of example, variousbelow-described components of FIG. 2 may be used to provide wirelesscommunication of analyte (e.g., glucose) data, for example among/betweenanalyte sensor system 308, display devices 310, partner devices 315,and/or one or more server systems 334, and so on.

As shown in FIG. 2, system 200 may include analyte sensor system 308,one or more display devices 310, and/or one or more partner devices 315.Additionally, in the illustrated embodiment, system 200 includes serversystem 334, which can in turn includes server 334 a coupled to processor334 c and storage 334 b. Analyte sensor system 308 may be coupled todisplay devices 310, partner devices 315, and/or server system 334 viacommunication media 305. Some details of the processing, gathering, andexchanging of data, and/or executing actions (e.g., providingmedicaments or related instructions) by analyte sensor system 308,partner devices 315, and/or display device 310, etc., are providedbelow.

Analyte sensor system 308, display devices 310, and/or partner devices315 may exchange messaging (e.g., control signaling) via communicationmedia 305, and communication media 305 may also be used to deliveranalyte data to display devices 310, partner devices 315, and/or serversystem 334. As alluded to above, display devices 310 may include avariety of electronic computing devices, such as, for example, asmartphone, tablet, laptop, wearable device, etc. Display devices 310may also include analyte display device 110 that may be customized forthe display and conveyance of analyte data and related notificationsetc. Partner devices 315 may include medical devices, such as an insulinpump or pen, connectable devices, such as a smart fridge or mirror, keyfob, and other devices.

In embodiments, communication media 305 may be based on one or morewireless communication protocols, such as for example Bluetooth,Bluetooth Low Energy (BLE), ZigBee, WiFi, IEEE 802.11 protocols,Infrared (IR), Radio Frequency (RF), 2G, 3G, 4G, 5G, etc., and/or wiredprotocols and media. It will also be appreciated upon studying thepresent disclosure that communication media can be implemented as one ormore communication links, including in some cases, separate links,between the components of system 200, whether or not such links areexplicitly shown in FIG. 2 or referred to in connection therewith. Byway of illustration, analyte sensor system 308 may be coupled to displaydevice 310 via a first link of communication media 305 using BLE, whiledisplay device 310 may be coupled to server system 334 by a second linkof communication media 305 using a cellular communication protocol(e.g., 4G LTE/5G and the like). In embodiments, a BLE signal may betemporarily attenuated to minimize data interceptions. For example,attenuation of a BLE signal through hardware or firmware design mayoccur temporarily during moments of data exchange (e.g., pairing).

In embodiments, the elements of system 200 may be used to performoperations of various processes described herein and/or may be used toexecute various operations and/or features described herein with regardto one or more disclosed systems and/or methods. Upon studying thepresent disclosure, one of skill in the art will appreciate that system200 may include single or multiple analyte sensor systems 308,communication media 305, and/or server systems 334.

As mentioned, communication media 305 may be used to connect orcommunicatively couple analyte sensor system 308, display devices 310,partner devices 315, and/or server system 334 to one another or to anetwork. Communication media 305 may be implemented in a variety offorms. For example, communication media 305 may include one or more ofan Internet connection, such as a local area network (LAN), a personarea network (PAN), a wide area network (WAN), a fiber optic network,internet over power lines, a hard-wired connection (e.g., a bus), DSL,and the like, or any other kind of network connection or communicativecoupling. Communication media 305 may be implemented using anycombination of routers, cables, modems, switches, fiber optics, wires,radio (e.g., microwave/RF, AM, FM links etc.), and the like. Further,communication media 305 may be implemented using various wirelessstandards, such as Bluetooth®, BLE, Wi-Fi, IEEE 802.11, 3GPP standards(e.g., 2G GSM/GPRS/EDGE, 3G UMTS/CDMA2000, or 4G LTE/LTE-A/LTE-U, 5G, orsubsequent generation), etc. Upon reading the present disclosure, one ofskill in the art will recognize other ways to implement communicationmedia 305 for communications purposes and will also recognize thatcommunication media 305 may be used to implement features of the presentdisclosure using as of yet undeveloped communications protocols that maybe deployed in the future.

Further referencing FIG. 2, server 334 a may receive, collect, and/ormonitor information, including analyte data, medicament data, andrelated information, from analyte sensor system 308, partner devices 315and/or display devices 310, such as input responsive to the analyte dataor medicament data, or input received in connection with an analytemonitoring application running on analyte sensor system 308 or displaydevice 310, or a medicament delivery application running on displaydevice 310 or partner device 315. As such, server 334 a may receive,collect, and/or monitor information from partner devices 315, such as,for example, information related to the provision of medicaments to auser and/or information regarding the operation of one or more partnerdevices 315. Server 334 a may also receive, collect, and/or monitorinformation regarding a user of analyte sensor system 308, displaydevices 310, and/or partner devices 315.

In embodiments, server 334 a may be adapted to receive such informationvia communication media 305. This information may be stored in storage334 b and may be processed by processor 334 c. For example, processor334 c may include an analytics engine capable of performing analytics oninformation that server 334 a has collected, received, etc. viacommunication media 305. In embodiments, server 334 a, storage 334 b,and/or processor 334 c may be implemented as a distributed computingnetwork, such as a Hadoop® network, or as a relational database or thelike. The aforementioned information may then be processed at server 334a such that services may be provided to analyte sensor system 308,display devices 310, partner devices 315, and/or a user(s) thereof. Forexample, such services may include diabetes management feedback for theuser.

In embodiments, a database may be implemented in server system 334 thatmay pair user accounts to one or more analyte sensor systems 308 usingcommunication media 305. Based on, for example, an expected lifetime ofindividual components or one or more groups of components of analytesensor system 308, or analyte sensor system 308 as a whole, and/or basedon diagnostic feedback received by analyte sensor system 308, serversystem 334 may be able to determine if a given analyte sensor system 308or component or group(s) of components thereof is expired or passed itsuseful life. A user may receive an indication, notification, alert, orwarning, for example, on display device 310 and/or through analytesensor system 308, from server system 334, that analyte sensor system308 or a component or group(s) of components thereof has expired orpassed its useful life or will do so soon or within a given amount oftime. In embodiments, a user may receive an indication, notification,alert, or warning on display device 310 from server system 334 about theexpected lifetime of analyte sensor system 308 or a component orgroup(s) of components thereof.

Server 334 a may include, for example, an Internet server, a router, adesktop or laptop computer, a smartphone, a tablet, a processor, amodule, or the like, and may be implemented in various forms, including,for example, an integrated circuit or collection thereof, a printedcircuit board or collection thereof, or in a discretehousing/package/rack or multiple of the same. In embodiments, server 334a at least partially directs communications made over communicationmedia 305. Such communications may include the delivery of analyte data,medicament data, and/or messaging related thereto (e.g., advertisement,authentication, command, or other messaging). For example, server 334 amay process and exchange messages between and/or among analyte sensorsystem 308, display devices 310, and/or partner devices 315 related tofrequency bands, timing of transmissions, security/encryption, alarms,alerts, notifications, and so on. Server 334 a may update informationstored on analyte sensor system 308, partner devices 315, and/or displaydevices 310, for example, by delivering applications thereto or updatingthe same, and/or by reconfiguring system parameters or other settings ofanalyte sensor system 308, partner devices 315, and/or display devices310. Server 334 a may send/receive information to/from analyte sensorsystem 308, partner devices 315, and/or display devices 310 in realtime, periodically, sporadically, or on an event-drive basis. Further,server 334 a may implement cloud computing capabilities for analytesensor system 308, partner devices 315, and/or display devices 310.

With the above description of aspects of the presently disclosed systemsand methods for wireless communication of analyte data, examples of somespecific features of the present disclosure will now be provided. Itwill be appreciated by one of skill in the art upon studying the presentdisclosure that these features may be implemented using aspects and/orcombinations of aspects of the example configurations described above,whether or not explicit reference is made to the same.

Analyte Data

Referring back to FIG. 1, as mentioned above, in embodiments, analytesensor system 8 is provided for measurement of an analyte in a host oruser. By way of an overview and an example, analyte sensor system 8 maybe implemented as an encapsulated microcontroller that makes sensormeasurements, generates analyte data (e.g., by calculating values forcontinuous glucose monitoring data), and engages in wirelesscommunications (e.g., via Bluetooth and/or other wireless protocols) tosend such data to remote devices (e.g., display devices 110, 120, 130,140, partner devices 136, and/or server system 134).

Analyte sensor system 8 may include: analyte sensor 10 configured tomeasure a concentration or level of the analyte in the host, and analytesensor electronics module 12 that is typically physically connected toanalyte sensor 10 before analyte sensor 10 is implanted in a user. Inembodiments, analyte sensor electronics module 12 includes electronicsconfigured to process a data stream associated with an analyteconcentration measured by analyte sensor 10, in order to generate sensorinformation that includes raw sensor data, transformed sensor data,and/or any other sensor data, for example. Analyte sensor electronicsmodule 12 may further be configured to generate analyte sensorinformation that is customized for respective display devices 110, 120,130, 140, partner devices 136, and/or server system 134. Analyte sensorelectronics module 12 may further be configured such that differentdevices may receive different sensor information and may further beconfigured to wirelessly transmit sensor information to such displaydevices 110, 120, 130, 140, partner devices 136, and/or server system134.

The term “analyte” as used herein is a broad term and is to be given itsordinary and customary meaning to a person of ordinary skill in the art(and is not to be limited to a special or customized meaning), andfurthermore refers without limitation to a substance or chemicalconstituent in a biological fluid (for example, blood, interstitialfluid, cerebral spinal fluid, lymph fluid or urine) that can beanalyzed. Analytes can include naturally occurring substances,artificial substances, metabolites, and/or reaction products. In someembodiments, the analyte for measurement by the sensor heads, devices,and methods is glucose. However, other analytes are contemplated aswell, including but not limited to acarboxyprothrombin; acylcarnitine;adenine phosphoribosyl transferase; adenosine deaminase; albumin;alpha-fetoprotein; amino acid profiles (arginine (Krebs cycle),histidine/urocanic acid, homocysteine, phenylalanine/tyrosine,tryptophan); andrenostenedione; antipyrine; arabinitol enantiomers;arginase; benzoylecgonine (cocaine); biotinidase; biopterin; c-reactiveprotein; carnitine; carnosinase; CD4; ceruloplasmin; chenodeoxycholicacid; chloroquine; cholesterol; cholinesterase; conjugated 1-ßhydroxy-cholic acid; cortisol; creatine kinase; creatine kinase MMisoenzyme; cyclosporin A; d-penicillamine; de-ethylchloroquine;dehydroepiandrosterone sulfate; DNA (acetylator polymorphism, alcoholdehydrogenase, alpha 1-antitrypsin, cystic fibrosis, Duchenne/Beckermuscular dystrophy, analyte-6-phosphate dehydrogenase, hemoglobin A,hemoglobin S, hemoglobin C, hemoglobin D, hemoglobin E, hemoglobin F,D-Punjab, beta-thalassemia, hepatitis B virus, HCMV, HIV-1, HTLV-1,Leber hereditary optic neuropathy, MCAD, RNA, PKU, Plasmodium vivax,sexual differentiation, 21-deoxycortisol); desbutylhalofantrine;dihydropteridine reductase; diptheria/tetanus antitoxin; erythrocytearginase; erythrocyte protoporphyrin; esterase D; fattyacids/acylglycines; free ß-human chorionic gonadotropin; freeerythrocyte porphyrin; free thyroxine (FT4); free tri-iodothyronine(FT3); fumarylacetoacetase; galactose/gal-1-phosphate;galactose-1-phosphate uridyltransferase; gentamicin; analyte-6-phosphatedehydrogenase; glutathione; glutathione perioxidase; glycocholic acid;glycosylated hemoglobin; halofantrine; hemoglobin variants;hexosaminidase A; human erythrocyte carbonic anhydrase I;17-alpha-hydroxyprogesterone; hypoxanthine phosphoribosyl transferase;immunoreactive trypsin; lactate; lead; lipoproteins ((a), B/A-1, ß);lysozyme; mefloquine; netilmicin; phenobarbitone; phenytoin;phytanic/pristanic acid; progesterone; prolactin; prolidase; purinenucleoside phosphorylase; quinine; reverse tri-iodothyronine (rT3);selenium; serum pancreatic lipase; sissomicin; somatomedin C; specificantibodies (adenovirus, anti-nuclear antibody, anti-zeta antibody,arbovirus, Aujeszky's disease virus, dengue virus, Dracunculusmedinensis, Echinococcus granulosus, Entamoeba histolytica, enterovirus,Giardia duodenalisa, Helicobacter pylori, hepatitis B virus, herpesvirus, HIV-1, IgE (atopic disease), influenza virus, Leishmaniadonovani, leptospira, measles/mumps/rubella, Mycobacterium leprae,Mycoplasma pneumoniae, Myoglobin, Onchocerca volvulus, parainfluenzavirus, Plasmodium falciparum, poliovirus, Pseudomonas aeruginosa,respiratory syncytial virus, rickettsia (scrub typhus), Schistosomamansoni, Toxoplasma gondii, Trepenoma pallidium, Trypanosomacruzi/rangeli, vesicular stomatis virus, Wuchereria bancrofti, yellowfever virus); specific antigens (hepatitis B virus, HIV-1);succinylacetone; sulfadoxine; theophylline; thyrotropin (TSH); thyroxine(T4); thyroxine-binding globulin; trace elements; transferring;UDP-galactose-4-epimerase; urea; uroporphyrinogen I synthase; vitamin A;white blood cells; and zinc protoporphyrin. Salts, sugar, protein, fat,vitamins, and hormones naturally occurring in blood or interstitialfluids can also constitute analytes in certain embodiments. The analytecan be naturally present in the biological fluid, for example, ametabolic product, a hormone, an antigen, an antibody, and the like.Alternatively, the analyte can be introduced into the body, for example,a contrast agent for imaging, a radioisotope, a chemical agent, afluorocarbon-based synthetic blood, or a drug or pharmaceuticalcomposition, including but not limited to insulin; ethanol; cannabis(marijuana, tetrahydrocannabinol, hashish); inhalants (nitrous oxide,amyl nitrite, butyl nitrite, chlorohydrocarbons, hydrocarbons); cocaine(crack cocaine); stimulants (amphetamines, methamphetamines, Ritalin,Cylert, Preludin, Didrex, PreState, Voranil, Sandrex, Plegine);depressants (barbituates, methaqualone, tranquilizers such as Valium,Librium, Miltown, Serax, Equanil, Tranxene); hallucinogens(phencyclidine, lysergic acid, mescaline, peyote, psilocybin); narcotics(heroin, codeine, morphine, opium, meperidine, Percocet, Percodan,Tussionex, Fentanyl, Darvon, Talwin, Lomotil); designer drugs (analogsof fentanyl, meperidine, amphetamines, methamphetamines, andphencyclidine, for example, Ecstasy); anabolic steroids; and nicotine.The metabolic products of drugs and pharmaceutical compositions are alsocontemplated analytes. Analytes such as neurochemicals and otherchemicals generated within the body can also be analyzed, such as, forexample, ascorbic acid, uric acid, dopamine, noradrenaline,3-methoxytyramine (3MT), 3,4-Dihydroxyphenylacetic acid (DOPAC),Homovanillic acid (HVA), 5-Hydroxytryptamine (5HT), and5-Hydroxyindoleacetic acid (FHIAA).

Preconnected Analyte Sensor System

As alluded to above with reference to FIG. 1, in embodiments, analytesensor 10 includes a continuous glucose sensor, for example, asubcutaneous, transdermal (e.g., transcutaneous), or intravasculardevice. In embodiments, such a sensor or device can analyze a pluralityof intermittent blood samples. Analyte sensor 10 can use any method ofanalyte measurement, including for example glucose-measurement,including enzymatic, chemical, physical, electrochemical,spectrophotometric, polarimetric, calorimetric, iontophoretic,radiometric, immunochemical, and the like.

In embodiments where analyte sensor 10 is a glucose sensor, analytesensor 10 can use any method, including invasive, minimally invasive,and non-invasive sensing techniques (e.g., fluorescence monitoring), orthe like, to provide a data stream indicative of the concentration ofglucose in a host. The data stream may be a raw data signal, which maybe converted into a calibrated and/or filtered data stream that can beused to provide a useful value of glucose to a user, such as a patientor a caretaker (e.g., a parent, a relative, a guardian, a teacher, adoctor, a nurse, or any other individual that has an interest in thewellbeing of the host).

A glucose sensor can be any device capable of measuring theconcentration of glucose. According to one example embodiment describedbelow, an implantable glucose sensor may be used. However, it should beunderstood that the devices and methods described herein can be appliedto any device capable of detecting a concentration of an analyte,glucose for example, and providing an output signal that represents theconcentration of the analyte, again glucose for example (e.g., as a formof analyte data).

In embodiments, analyte sensor 10 is an implantable glucose sensor, suchas described with reference to U.S. Pat. No. 6,001,067 and U.S. PatentPublication No. US-2005-0027463-A1. In embodiments, analyte sensor 10 isa transcutaneous glucose sensor, such as described with reference toU.S. Patent Publication No. US-2006-0020187-A1. In embodiments, analytesensor 10 is configured to be implanted in a host vessel orextracorporeally, such as is described in U.S. Patent Publication No.US-2007-0027385-A1, co-pending U.S. Patent Publication No.US-2008-0119703-A1 filed Oct. 4, 2006, U.S. Patent Publication No. US2008-0108942-A1 filed on Mar. 26, 2007, and U.S. Patent Application No.US-2007-0197890-A1 filed on Feb. 14, 2007. In embodiments, thecontinuous glucose sensor includes a transcutaneous sensor such asdescribed in U.S. Pat. No. 6,565,509 to Say et al., for example. Inembodiments, analyte sensor 10 is a continuous glucose sensor thatincludes a subcutaneous sensor such as described with reference to U.S.Pat. No. 6,579,690 to Bonnecaze et al. or U.S. Pat. No. 6,484,046 to Sayet al., for example. In embodiments, the continuous glucose sensorincludes a refillable subcutaneous sensor such as described withreference to U.S. Pat. No. 6,512,939 to Colvin et al., for example. Thecontinuous glucose sensor may include an intravascular sensor such asdescribed with reference to U.S. Pat. No. 6,477,395 to Schulman et al.,for example. The continuous glucose sensor may include an intravascularsensor such as described with reference to U.S. Pat. No. 6,424,847 toMastrototaro et al., for example.

Before system activation, analyte sensor electronics module 12 istypically maintained in a lower power mode in order to conserve ormanage battery capacity. Analyte sensor electronics module 12, in orderto begin gathering analyte data in an active power state, shouldgenerally be activated reliably. For example, it may be preferable notto activate analyte sensor electronics module 12 until around the timewhen analyte sensor 10 is implanted in a host. This may help maintainmore accurate sensor calibration, may reduce power consumption, and/ormay generally increase analyte measurement accuracy, etc. In someembodiments, the activation of analyte sensor electronics module 12and/or certain circuits thereof may at least primarily occur prior toanalyte sensor 10 implantation (e.g., within 5 minutes, 1 minute, 30 s,10 s, 1 s, or less than is before implantation, or the like). In someembodiments, activation of analyte sensor electronics module 12 may atleast primarily occur during or substantially during implantation (e.g.,at least partially while analyte sensor 10 is translating to thedeployed position). In some embodiments, activation of analyte sensorelectronics module 12 may at least primarily occur after the time ofanalyte sensor 10 implantation (e.g., within less than 1 s, 1 s, 5 s, 30s, 1 min, 3 mins, 5 mins, 10 mins, more than 10 mins after implantation,or the like). In embodiments, it is preferred for analyte sensorelectronics module 12 to exit a lower power state at or shortly beforethe time around which analyte sensor 10 is implanted. This may allow thetime of implantation to be more accurately recorded.

In systems that are not pre-connected, analyte sensor 10 and analytesensor electronics module 12 are usually mechanically and electricallyconnected for the first time after analyte sensor 10 is implanted intothe user. Electrodes of analyte sensor electronics module 12 aretypically monitored to detect an analyte related signal when analytesensor electronics module 12 is coupled to an already implanted analytesensor 10. Analyte sensor system 8 may then be activated in response tothe coupling and detection of a particular level or characteristic ofanalyte in a user. However, in a pre-connected analyte sensor system 8,analyte sensor 10 may be electromechanically coupled to analyte sensorelectronics module 12 before analyte sensor system 8 is delivered touser and thus analyte sensor electronics module 12 is already coupled toanalyte sensor 10 at the time of sensor implantation. As alluded toabove, this pre-coupling or pre-connection can lead to erroneous wakeupsor activation from a lower power state, for example due to a signalgenerated by analyte sensor system 8 prior to sensor implantation (e.g.,in situations of high humidity, static electricity, current leakage, ornoise). Also, to improve accuracy in converting a sensor signal to ananalyte value with a sensor processing algorithm, it may be preferredthat analyte sensor 10 is not voltage biased by analyte sensorelectronics module 12 before implantation.

Operations that may cause changes to properties of analyte sensor 10should generally be minimized before implantation. Accordingly, it maybe preferred to avoid or at least reduce the occurrence of voltagebiasing analyte sensor 10 before implantation. Applying voltage bias toanalyte sensor 10 on a relatively long-term basis (e.g., during storage)may cause analyte sensor 10 to have a shorter than intended use lifefollowing implantation. This may be due to, for example, consumption ofreference or enzyme capacity that may be contained on analyte sensor 10.Moreover, an analyte processing algorithm that may be used by analytesensor system 8 may rely upon characterized performance values ofanalyte sensor 10. These characterized performance values may include abaseline signal, analyte sensitivity, signal drift, lot performancemetrics, curve fitting variables, tabular values, calibration codes,and/or additional factors that may be used as part of a signalprocessing algorithm in connection with determining analyte values.Thus, in some instances particularly for factory calibrated analytesensors 10, it can be important to have a relatively accurate estimateof analyte sensor 10 performance parameters and/or characteristics atthe time of implantation into a user, in order to enable accurategeneration of analyte values. Significant durations (e.g., during shelflife) of applying a voltage bias across analyte sensor 10 may causedeviations from one or more predetermined performance metrics. This maytend to decrease the accuracy of analyte values determined using asensor processing algorithm to convert one or more measured analytesensor 10 signals to analyte values after analyte sensor 10implantation. Additionally, deviation from the calibrated state ofanalyte sensor 10 during storage can cause the algorithm to report lessaccurate or inaccurate analyte values.

Furthermore, the amount of power (e.g., mW) used by the circuitry and/orother components (e.g., within analyte sensor electronics module) thatcontrol activation of analyte sensor system 8 should generally beminimized, reduced, and/or considered in connection with making systemlevel performance tradeoffs where possible. For measurements generatedusing analyte sensor 10 or other circuits or components, care shouldgenerally be taken to minimize, reduce, and/or control power usage priorto activation of analyte sensor system 8. Power budgets may be at leastsomewhat limited by a battery capacity of analyte sensor system 8. Thus,analyte sensor system 8 may primarily remain in a lower power or mostlynon-operational state prior to activation, and techniques used tocontrol system activation and/or exit the lower power state may consumea small portion of available power.

In embodiments, lower power consumption is achieved by, for example,selecting a reduced or minimum viable polling or sampling frequency forpower usage and detectability of a system activating event and/ortrigger. In some cases, a sampling or polling frequency used to monitoran activating event/trigger/characteristic may be varied based on thetype of detection scheme that is being used (e.g., capacitancemeasurement versus accelerometer input, as will be described below). Inconnection with reducing power consumption, lower power state machinesthat perform measurement and logic functions to trigger system wakeupwithout powering up a main system processor may be employed. Forexample, a lower power state can be effectively maintained throughemploying a reduced and/or variable, adaptable, programmable, and/orconfigurable polling or sampling frequency. In some cases, this lowerpower state can be facilitated through the use of low power statemachines. The lower power state, in which power consumption can becontrolled/reduced, can in this fashion largely be maintainednotwithstanding periodic polling/sampling that may be done in connectionwith detecting an activation event for analyte sensor system 8.

In embodiments, analyte sensor system 8 is made more robust to falsewake ups, and if a false wake up is detected, the system can return to alower power state. For example, if at any point analyte sensor system 8detects that analyte sensor 10 generates a signal that does not satisfya threshold or one or more characteristics indicative of a wakeup event,analyte sensor system 8 may return to or remain in the lower powerstate. By way of example, in such a lower power state, there may be nodata transmission or analyte measurements by analyte sensor electronicsmodule 12. Lower power and active states may be implemented primarily infirmware in many cases, but some wake up circuits may have hardwareintegration to enable more robust activation detection mechanisms (e.g.,discharging a capacitor, etc., as will be described herein).

Accordingly, embodiments of the present disclosure involve employingmultiple techniques and/or mechanisms/components/circuits for detectingand confirming that a lower power state of pre-connected analyte sensorsystem 8 may be changed. By way of illustration, such a change mayentail analyte sensor system 8 being activated, caused to exit a lowerpower state, and/or caused to move into a more active state. This maytake place in response to conditions that indicate analyte sensor 10 hasbeen implanted into a user. In one example, analyte sensor system 8 candetect an analyte using analyte sensor 10 and a potentiostat or othermeasurement device that applies a voltage bias on one or more electrodesof analyte sensor 10 and measures the resulting amount of current thatflows. This current and/or related signals may be referred to herein asa primary signal.

Additionally, by way of example, there may be a characteristic signalprofile that can be measured when analyte sensor 10 is implanted intotissue of a host. Such a characteristic signal profile can result fromchanges in analyte sensor 10 when analyte sensor 10 is first exposed tothe tissue environment, for example due to membrane hydration and/orresulting changes in analyte and/or ionic concentrations. Suchcharacteristic signal profiles may be referred to herein as secondarysignals. In embodiments, secondary signals may include or involve theuse of capacitance, impedance, or other electrical measurements ofanalyte sensor 10.

[The signal characteristics of a primary signal measured using analytesensor 10 (e.g., voltage or current or the like) along with in vivoand/or in factory calibration information for analyte sensor 10 may beused by an analyte processing algorithm implemented, for example, usinganalyte sensor electronics module 12 to convert the primary signal toanalyte concentration levels. The signal characteristics of the primarysignal may change over time. Examples of signal profiles for analytevalues (e.g., which may be measured in mg/dL) or for other measurementstaken using one or more electrodes of analyte sensor 10 (e.g., voltage,current, digital “counts,” etc.) include the following: gradient ofsignal, threshold of signal, integration over time, slope, balance,range, or any other characteristics that may be used to specificallyidentify the signal. Such signal profiles/characteristics can bepredefined in analyte sensor system 8.

Employing multiple of the above-referenced techniques and other meansfor activation/state change, etc., in a pre-connected analyte sensorsystem 8 can better enable accurately detecting implantation of analytesensor 10 into a user, which in turn has numerous advantages. Forexample, accurately detecting or approximating an implantation time foranalyte sensor 10 can better enable a factory calibrated system. By wayof example, a signal processing algorithm implemented using, e.g.,processor 535 of analyte sensor system 308 (referencing FIG. 5 by way ofexample), may use one or more techniques in the conversion of an analytesensor signal to an estimated analyte value. During different periods ofan analyte sensor 10 lifecycle (e.g., less than one hour afterimplantation, less than 4 hours after implantation, more than 4 hoursafter implantation, etc.), these conversion techniques may providedifferent levels of accuracy with respect to the conversion. Inembodiments, some of these techniques may rely on predetermined signalprofiles that are time dependent. Therefore, recording and/or estimatinga more accurate implantation time of analyte sensor 10 may be beneficialfor selecting a signal processing algorithm and addressing variations ina processing technique that may occur as a function of time. An analytesensor system 8 that uses such techniques/means may thus have improvedoverall accuracy as well as improved performance upon implantation ofanalyte sensor 10 (e.g., as performance upon implantation may beimpacted, including by errors that may be induced from not accuratelyassessing/detecting a time at which analyte sensor 10 is implanted). Forexample, inaccuracies may be introduced due to the slope of asensitivity of analyte sensor 10 following implantation, or due tobackground signal changes that may occur following implantation ofanalyte sensor 10.

Accurate detection of implantation time can also enable faster startupof analyte sensor system 8 in terms of providing analyte information toa user. For example, a more accurate implantation time may be useful foran analyte calculation algorithm implemented in analyte sensor system 8to determine an appropriate time point to begin displaying analyteinformation to a user (e.g., a confidence level between signal andanalyte conversion). Due to the slope of analyte related signal changeswithin a first interval of time (e.g., 2 hours, etc.) after implantationof analyte sensor 10, implantation timing errors may result ininappropriate predictions to the signal response and analyte signal.Recognizing the time point in the characteristic signal decay curve mayenable analyte sensor system 8 and/or devices operating in conjunctiontherewith to display or provide analyte information (e.g., on a displaydevices 110, 120, 130, 140, to server system 134, and/or to partnerdevice(s) 136, with reference by way of example to FIG. 1) relativelysooner than if the implantation time of analyte sensor 10 was lessaccurately determined (e.g., within 2 hours, 1 hour, 30 minutes, 15minutes, or less).

Additionally, accurate detection of the implantation time of analytesensor 10 can assist in preventing reuse of analyte sensor 10. Detectionof sensor implantation time by electronics module 12 can enable a higherreliability metric versus a reliance on the user providing notificationof insertion/implantation time. For example, disconnection and/orimplantation characteristics can distinguish a newly inserted analytesensor 10 from an attempt of the user to restart an expired analytesensor 10.

As an additional example, accurate detection/estimation of analytesensor 10 implantation time may enable faster connectivity establishmentbetween analyte sensor electronics module 12 and devices connectablethereto (see, e.g., FIG. 1). With a more accurate detection and/orestimation of analyte sensor 10 implantation time, analyte sensor system8 may be placed in a state to establish and enter into communicationwith multiple devices based on being near to or at the time ofimplantation. For example, analyte sensor system 8 may be able to entera pairing state within a relatively short time of implantation (e.g.,less than 10 to 15 minutes) such that display devices (e.g., displaydevices 110, 120, 130, 140, partner device(s) 136, etc., referencingFIG. 1 by way of example) may be able to wirelessly connect to analytesensor system 8. A more accurate detection of analyte sensor 10implantation time may also be used to trigger alternative connectionprofiles to encourage faster connection, for example, pairing,encryption, advertisement characteristics, etc. That is, for example, amore definitive wakeup event can be used to facilitate a more aggressiveconnection model as between analyte sensor system 8 and a deviceconnectable thereto (e.g., sending advertisement packets at a fasterrate or the like). This may enable faster connection establishment andmay also provide the user with near real time feedback that analytesensor system 8 is receiving a signal and is connected to the displaydevice.

An additional example of an advantage associated with accurateestimation of analyte sensor 10 implantation time that can be enabled bymore robust wakeup techniques for analyte sensor 8 is improving errordetection. Knowing the predicted profile and monitoring the signalmeasured using analyte sensor 10 from the time of implantation canenable recognition of deviations from expected characteristics ofimplantation in the signal profile. This can be enabled by knowledge ofthe implantation time of analyte sensor 10 as well as the ability toanalyze the analyte signal at the time of implantation (for example, asignal that is associated with implantation is less likely to be misseddue to analyte sensor system 8 being in a lower power state). Theability to recognize such deviations can trigger system safety oraccuracy errors that may be hazardous for a user of analyte sensorsystem 8. For example, analyte sensors 10 that are physically damaged(e.g., membrane breaches, tears, manufacturing errors, etc.) may havedifferent characteristic signals after implantation.

Yet another example of an advantage associated with accurate estimationof analyte sensor 10 implantation time is faster wakeup time for analytesensor system 8, which may also enable improved error detectionabilities. Risks of user variation in analyte sensor 10 implantationtime may be reduced by using analyte sensor system 8 that ispre-connected and by detecting implantation time for analyte sensor 10automatically or semi-automatically. Analyte sensor 10 that has beeninserted into the incorrect tissue location (for example, not under theskin, or into muscle/fascia rather than a desired tissue layer) may havedifferent characteristic signals than expected following insertion.Faster wakeup time may enable such issues to be detected more quicklyfollowing implantation, thus improving overall error detectionperformance associated with analyte sensor system 8.

FIG. 3A illustrates a perspective view of an on-skin sensor assembly 360that may be used in connection with a preconnected analyte sensor system8, in accordance with some embodiments. For example, on-skin analytesensor assembly 360 may include analyte sensor system 8, with referenceby way of example to FIG. 1. On-skin sensor assembly 360 may include anouter housing with a first, top portion 392 and a second, lower portion394. In embodiments, the outer housing may include a clamshell design.On-skin sensor assembly 360 may include, for example, similar componentsas analyte sensor electronics module 140 described above in connectionwith FIG. 1, for example, a potentiostat, a power source for providingpower to analyte sensor 10, signal processing components, data storagecomponents, and a communication module (e.g., a telemetry module) forone-way or two-way data communication, a printed circuit board (PCB), anintegrated circuit (IC), an Application-Specific Integrated Circuit(ASIC), a microcontroller, and/or a processor.

As shown in FIG. 3A, the outer housing may feature a generally oblongshape. The outer housing may further include aperture 396 disposedsubstantially through a center portion of outer housing and adapted forsensor 338 and needle insertion through a bottom of on-skin sensorassembly 360. In embodiments, aperture 396 may be a channel or elongatedslot. On-skin sensor assembly 360 may further include an adhesive patch326 configured to secure on-skin sensor assembly 360 to skin of thehost. In embodiments, adhesive patch 326 may include an adhesivesuitable for skin adhesion, for example a pressure sensitive adhesive(e.g., acrylic, rubber-based, or other suitable type) bonded to acarrier substrate (e.g., spun lace polyester, polyurethane film, orother suitable type) for skin attachment, though any suitable type ofadhesive is also contemplated. As shown, adhesive patch 396 may featurean aperture 398 aligned with aperture 396 such that sensor 338 may passthrough a bottom of on-skin sensor assembly 360 and through adhesivepatch 396.

FIG. 3B illustrates a bottom perspective view of on-skin sensor assembly360 of FIG. 3A. FIG. 3B further illustrates aperture 396 disposedsubstantially in a center portion of a bottom of on-skin sensor assembly360, and aperture 398, both adapted for sensor 338 and needle insertion.

FIG. 4 illustrates a cross-sectional view of on-skin sensor assembly 360of FIGS. 3A and 3B. FIG. 4 illustrates first, top portion 392 andsecond, bottom portion 394 of the outer housing, adhesive patch 326,aperture 396 in the center portion of on-skin sensor assembly 360,aperture 398 in the center portion of adhesive patch 326, and sensor 338passing through aperture 396. The electronics unit, previously describedin connection with FIG. 3A, may further include circuit board 404 andbattery 402 configured to provide power to at least circuit board 404.

Turning now to FIG. 5, a more detailed functional block diagram ofanalyte sensor system 308 (discussed above, for example, in connectionwith FIGS. 1 and 2) is provided. As shown in FIG. 5, analyte sensorsystem 308 may include analyte sensor 530 (e.g., which may also bedesignated with the numeral 10 in FIG. 1) coupled to analyte sensormeasurement circuitry 525 for processing and managing sensor data.Sensor measurement circuitry 525 may be coupled toprocessor/microprocessor 535 (e.g., which may be part of item 12 in FIG.1). In some embodiments, processor 535 may perform part or all of thefunctions of sensor measurement circuitry 525 for obtaining andprocessing sensor measurement values from analyte sensor 530.

Processor 535 may be further coupled to a radio unit or transceiver 510(e.g., which may be part of item 12 in FIG. 1) for sending sensor andother data and receiving requests and commands and other signaling froman external device, such as display device 310 (referencing FIG. 2 byway of example). Display device 310 may be used to display or otherwiseprovide the sensor data (or analyte data) or data derived therefrom to auser, server system 334, and/or partner device 315. Partner device 315may utilize sensor data or a derivative data derived therefrom in theadministration of medicaments (e.g., insulin) and/or diabetes managementguidance to the user. As used herein, the terms “radio unit” and“transceiver” may be used interchangeably and generally refer to adevice that can wirelessly transmit and receive data. Analyte sensorsystem 308 may further include storage 515 (e.g., which may be part ofitem 12 in FIG. 1) and real time clock (RTC) 540 (e.g., which may bepart of item 12 in FIG. 1), for storing and tracking sensor and otherdata.

Analyte sensor system 308 may also include activation detection circuit520. Activation detection circuit 520 may optionally operate inconjunction with activation detection component 545. Activationdetection component 545 may be integral to analyte sensor system 308,may be a component attachable thereto, and/or may be external thereto.Examples of activation detection circuit 520 may include one or more of(1) measurement circuitry that measures electrical characteristicsassociated with analyte sensor 10, such as capacitance or impedance,etc.; (2) proximity detection circuitry, which may use, for example,capacitive sensing, inductive sensing, magnetic detection, sonicdetection, etc.; (3) temperature measurement circuitry; (4)accelerometer circuitry; (5) radio and/or antenna circuitry forNFC/RFID; (6) air pressure detection circuitry; (7) audio circuitry; (8)optical detection circuitry; (9) conductivity measurement circuitry;(10) switch detection circuitry; (11) strain detection circuitry; and soon. Activation detection circuitry 520 and/or activation detectioncomponent 545 may also use or include logic circuitry adapted to executestored instructions or computer code to perform functionalities asdescribed herein with respect to detecting activation events/triggersand otherwise enabling activation of analyte sensor system 8 based upontriggering events/conditions and/or measurement of analytevalues/characteristics/profiles. Additional details regarding activationdetection circuit 520 and activation detection component 545 arediscussed further elsewhere herein.

Analyte sensor system 308 in example implementations gathers analytedata using sensor 530 and transmits the same or a derivative thereof todisplay device 310, partner device 315, and/or server system 334. Datapoints regarding analyte values may be gathered and transmitted over thelife of sensor 530. New measurements and/or related information may betransmitted often enough for a remote device/individual to adequatelymonitor analyte (e.g., glucose) levels.

It is to be appreciated that some details of the processing, gathering,and exchanging data by analyte sensor system 308, partner devices 315,and/or display device 310 etc. are provided elsewhere herein. It will beappreciated upon studying the present disclosure that analyte sensorsystem 308 may contain several like components that are described withrespect to FIG. 1 or 2, at least for some embodiments herein. Thedetails and uses of such like components may therefore be understoodvis-à-vis analyte sensor system 308 even if not expressly described herewith reference to FIG. 5.

Exiting a Low Power State

As discussed above, embodiments of the present disclosure concern thetiming for activating analyte sensor system 308 or causing the same toexit a lower power mode, particularly where analyte sensor system 308 isa pre-connected system. For example, in such a pre-connected system,analyte sensor 10 may be mechanically and electrically coupled toanalyte sensor electronics module 12 before analyte sensor 10 isimplanted into a host. There are several different time periods at whichanalyte sensor system 308 may exit a lower power mode, with each timeperiod typically having associated trade-offs.

One time period at which analyte sensor system 308 may exit a lowerpower state is upon a user opening a package containing analyte sensorsystem 308 or upon a user removing analyte sensor system 308 from such apackage. For example, using a switch, magnet, or other means describedherein, the analyte sensor system 308 could be caused to exit the lowerpower state in response to the opening of a shipping box or sterile packfor analyte sensor system 308, in response to the removal of a cap/lidfor the system, and/or in response to peeling foil/Tyvek packaging forthe system. However, exiting a lower power state at this time period mayhave a higher probability of not immediately preceding insertion ofanalyte sensor 10 into a user, therefore potentially increasing thepower usage requirement of analyte sensor system 308. For example, ifmultiple analyte sensor systems 308 are typically delivered to the userin a single package (e.g., a four-pack), all delivered analyte sensorsystems 308 may be activated in this scenario even though only one ofthe analyte sensor systems 308 may likely be used in the near term. Inanother example, after the user removes a packaging lid for analytesensor system 308, thus triggering analyte sensor 10 to be biased, theuser may delay implantation of analyte sensor 10 until after analytesensor 10 is biased or after other secondary verification means areemployed, thus wasting any power used to employ such secondaryverification means (e.g., NFC, accelerometer, impedance measurement,etc., as described in detail herein) and potentially decreasing theaccuracy of analyte sensor 10 due to calibration drift that may resultfrom applying bias.

Another example time period at which analyte sensor system 308 may exita lower power state is when analyte sensor system 308 is in anapplicator but has not yet been deployed. Example techniques that may beemployed for exiting the lower power state at this time period includemechanical means (e.g., a bridge, etc.) and electrical or othernonmechanical means (e.g., NFC, magnetic, sonic detection, etc.), aswill be discussed in further detail below. In certain situations, thistime period may be preferred because it may be easier to detectactivation events, for example, because typically detectable events thatmay occur (such as analyte sensor system 308 changing positions relativeto the applicator) during this time period may occur over a longerperiod of time, relative to, e.g., detectable events that may beassociated with analyte sensor system 308 deployment. This time periodmay also be preferred for detecting activation related indicatorsbecause it is usually closer in time to implantation of analyte sensor10, thus helping reduce user-created false wakeups, such as, forexample, that may occur when the user unboxes analyte sensor system 308but then chooses not to implant analyte sensor 10. Thus, events that mayoccur in the applicator for analyte sensor system 308 may serve as moreeffective markers for estimating implantation time and/or activatinganalyte sensor system 308 or causing the same to exit a lower powerstate.

Yet another time period at which analyte sensor system 308 can be causedto exit a lower power state is during the deployment of analyte sensorsystem 308 (e.g., the translation of analyte sensor 10 from the proximalposition to the distal position into the tissue of a host). Here again,either electrical or electro-mechanical means, or both, may be used totrigger an activation of analyte sensor system 308. One potential issuewith using deployment-related events for activation purposes, however,may be that deployment usually occurs over a shorter time periodrelative to activation related indicators that occur in association withthe applicator, for example (as described above), so the signal or eventmay be easier to miss or harder to detect relative to applicator-relatedevents.

Another time period that may be used for causing analyte sensor system308 to exit a lower power state may be after the implantation of analytesensor 10. Mechanical, electrical, and/or electromechanical (or othernonmechanical) means may be employed for triggering an activation ofanalyte sensor system 308. Additionally, or alternatively, analytesensor 10 itself may be used for triggering analyte sensor system 308 towake up or exit a lower power state. By way of example, a measuredcapacitance of analyte sensor 10 and/or a measured value for a membraneimpedance of the sensor and/or a measured value of a user's skinimpedance may be compared to a known condition (e.g., a threshold value)such that the comparison can be used to indicate implantation of analytesensor 10. However, after the insertion of analyte sensor 10, any delayin detecting insertion of analyte sensor 10 can impact the accuracy ofan analyte processing algorithm used to calculate analyte values.Furthermore, such delay can impact analyte sensor system 308 fromexecuting other operations that it is capable of performing, such as,pairing with display devices 310, partner devices 315, etc.,communicating analyte values to display devices 310, partner devices315, etc., and the like.

Using Signals from the Analyte Sensor to Exit Lower Power State

As referenced above, embodiments of the present disclosure involvedetecting implantation of analyte sensor 10 into a user, including, forexample, where implantation is detected using analyte sensor 10, andcausing analyte sensor system 308 to activate and/or exit a lower powerstate, in an accurate and power-efficient manner. In exampleembodiments, an analyte signal from analyte sensor 10 is used foractivation purposes. For example, activation detection circuit 520 mayuse one or more signals from a potentiostat to generate the analytesignal and/or for example, to detect/measure current flow throughanalyte sensor 10 (or analyte sensor 530, referencing FIG. 5, though itshould be appreciated that these components may be referred tointerchangeably in some cases) over time. Such signals may be quantifiedin units such as pA (current flow), pW (power), or counts (digitalvalues converted from an analog value such as a voltage, a current, apower and/or a time), and these values can be used for purposes oftriggering analyte sensor system 308 to exit a lower power state. Forexample, a benchmark threshold of current units may be used fortriggering a wake-up or activation of analyte sensor system 308.However, basing such triggering on a predetermined current unit (e.g.,counts) threshold can sometimes result in false wakeups or missedwakeups. For example, if the predetermined threshold is satisfied eventhough analyte sensor 10 has not been properly implanted into a host(e.g., via electrostatic discharge that may occur prior to deployment,for example while analyte sensor 10 is in packaging), then analytesensor system 308 may be caused to wake up or enter an operational modein situations when it should remain in lower power state or storagemode.

Thus, embodiments of analyte sensor system 308 use a benchmark thresholdfor current measurements for analyte sensor 10 (e.g., of approximately Xcounts, where X may be, for example, 9,000 counts) that may generally bemeasured over a certain amount of time in units of seconds or minutes(e.g., 300 seconds or 5 minutes). In certain embodiments, thebenchmarked threshold can be monitored in the context of a persistentcondition, where the benchmarked threshold may be configured to be metor exceeded for a predetermined amount of time before an activation istriggered, thus helping ensure that analyte sensor system 308 shouldindeed wake up. For example, the persistent condition can includeconsistent-frequency current measurements (e.g., including digitalcounts in some cases) over a subset of a time duration used formeasuring current for activation purposes. For example, this can ensurethat the benchmark threshold is not reached based on an undesiredanomaly, such as a short duration spike of current (or, e.g., digitalcounts) within the time period for monitoring current through analytesensor 10 for purposes of activating analyte sensor system 308.

The measured current (e.g., number of received counts) for analytesensor 10 may be compared with a benchmark threshold (e.g., X counts,which can be approximately 9000 counts). Upon a determination that themeasured current (e.g., number of received counts) meets or exceeds thebenchmark threshold (e.g., X counts), processor 535, which may be partof or operation in conjunction with activation detection circuit 520,can initiate an operational mode of analyte sensor system 308. Forexample, analyte sensor system 308 may begin receiving/obtaining sensorinformation from analyte sensor 530. In some embodiments, for example,estimated analyte value data is then transmitted to one or more displaydevices 110, etc. That is, processor 535 can stay active andforward/communicate and/or process the sensor information (e.g.,current, digital counts, or the like) to transceiver 510 forcommunication to one or more display devices 110, partner devices 136,etc. However, if the determination was that the measured current (e.g.,number of received digital counts, etc.) did not meet or exceed thebenchmark threshold (e.g., X counts), analyte sensor system 308 mayremain in a lower power state and/or storage mode. Optionally, in somecases, and subsequent to the determination that the measured current(e.g., number of received counts, or the like) meets or exceeds thebenchmark threshold (e.g., count-related threshold), anotherdetermination can be made to determine whether the measured value (e.g.,number of received counts, etc.) meets or exceeds a second benchmark(e.g., count threshold (U)) for a second period of time (V). This mayresult in a system that is more robust to false wakeups that mightresult from anomalies associated with the analyte sensor signal.

FIG. 7A is a schematic diagram of equivalent circuit model 700 foranalyte sensor 10, in accordance with embodiments of the presentdisclosure. Sensor circuit model 700 can represent electrical propertiesof analyte sensor 10, such as an embodiment of a continuous glucosesensor. Circuit 700 includes first terminal 704 (e.g., which may be aworking electrode) and second terminal 702 (e.g., which may be areference electrode). Operatively connected in serial to second terminal702 is Rsolution 712, representative of a resistance of bulk 706 betweenfirst and second terminals 704 and 702. Bulk 706 can be a liquid (e.g.,interstitial fluid) or other medium in which analyte sensor 10 isplaced, such as a buffer solution in the example of a bench laboratorystudy, or, in the example of the use as a subcutaneously placed analytesensor 10, bulk 706 can be representative of the subcutaneous tissueenvironment between first and second terminals 704 and 702.

Operatively connected to Rsolution 712 is Cmembrane 716, representativeof a capacitance of membrane 708 of analyte sensor 10, and Rmembrane714, representative of a resistance of membrane 708 of analyte sensor10. A parallel network of Cdouble layer 718 and Rpolarization 720 areoperatively connected to Rmembrane 714. The parallel network of Cdoublelayer 718 and Rpolarization 720 is representative of the reactionsoccurring at the surface of a platinum interface of first terminal 704.In particular, Cdouble layer 718 is representative of the charge that isbuilt up when a working electrode (e.g., platinum) is in bulk 706 andRpolarization 720 is the polarization resistance of the electrochemicalreactions that may occur at working electrode interface 710.

In example embodiments, a non-analyte signal is generated using analytesensor 10 and used for purposes of activating analyte sensor system 308and/or causing analyte sensor system 308 to exit a lower power mode. Onesuch non-analyte signal includes a signal that may represent certainelectrical, physical, or other properties of analyte sensor 10. Forexample, a stimulus signal may be used to determine certain propertiesof analyte sensor 10.

According to embodiments, a capacitance of analyte sensor 10 may bedetected and used to trigger analyte sensor system 308 to activateand/or exit a lower power state. For example, the capacitance of analytesensor 10 may change when analyte sensor 10 membrane is hydrated orplaced within an environment having a higher or lower humidity.Activation detection circuit 520 may include a circuit that responds toanalyte sensor 10 capacitance and drives a time varying signal (e.g., asquare wave, voltage step, alternating current signal, or the like)through analyte sensor 10, detecting how that signal may be affected byanalyte sensor 10 capacitance. How analyte sensor 10 responds to thedriving signal can be indicative of a capacitance associated withanalyte sensor 10. For example, a minimum level of capacitance foranalyte sensor 10 could be required to detect a threshold response tothe driving signal. Accordingly, analyte sensor system 308 can useactivation detection circuit 520 to measure a metric indicative ofcapacitance for analyte sensor 10 and, based on that capacitance metric,a determination can be made as to whether or not analyte sensor 10 hasbeen implanted in a host. It should be appreciated that the measuredcapacitance can include one or more of Cmembrane 716, Cdouble layer 718(referencing FIG. 7A by way of example), and other capacitances that maybe associated with analyte sensor 10. For example, a driving signalcould be passed through analyte sensor 10 between first and secondterminals 702 and 704, where the driving signal may then be affected byCmembrane 716, Cdouble layer 718, and other capacitances that may beassociated with analyte sensor 10 and used to approximate thosecapacitances and/or a total amount of capacitance that may load analytesensor 10.

Impedance is another characteristic of analyte sensor 10 that may bedetected and used to trigger analyte sensor system 308 to activateand/or exit a lower power state. FIG. 7B illustrates example plot 726 ofanalyte sensor 10 impedance value (e.g., in units of Ohms) 722 versustime from implantation 724 (e.g., in units of seconds). As shown,impedance value 722 of analyte sensor 10, after a certain amount of timefollowing implantation (e.g., 30 seconds), may begin to decrease. Asfurther shown, after an initial decay in impedance value 722, impedancevalue 722 largely stabilizes following a certain amount of time afterimplantation of analyte sensor 10. The change (e.g., decrease inimpedance value 722, or a rate of change of the impedance value, or thelike) that may result from implantation of analyte sensor 10 can be usedfor detecting/triggering activation.

FIG. 7C shows another example plot 734 of impedance value 730 (e.g., inunits of Ohms). FIG. 7C provides a plot of impedance value 730 versushydration 732 (e.g., in units of %), which may be a hydration associatedwith a membrane of analyte sensor 10. Generally, humidity outside thehuman body can cause a membrane hydration level that may be lower thanthe hydration level that may typically be associated with the membranewhen analyte sensor 10 is inside the human body. Accordingly, moisturein an environment, and the hydration levels that may result (e.g. of amembrane of analyte sensor 10), may be used to indicate that analytesensor 10 has or has not been implanted into the body of a host.Additionally, in some cases, certain environmental conditions (e.g.,humidity) may cause activation of analyte sensor system 308 even ifanalyte sensor 10 has not been inserted into a host's body.

Additionally, measurable electrical characteristics associated withanalyte sensor 10 may vary as a function of environmental humidity,moisture, and/or membrane hydration. The variation of such measurableelectrical characteristics (e.g., impedance, capacitance, etc.) as afunction of humidity, moisture, and/or hydration may in some cases besuch that the measurable electrical characteristics can serve as a morereliable indicator for activating analyte sensor system 308 or causinganalyte sensor system 308 to exit a lower power state than, for example,directly using humidity, hydration, and/or moisture level. For example,in some cases, humidity, moisture, and/or membrane hydration mayincrease for reasons other than analyte sensor 10 being inserted into ahost (e.g. high moisture levels within packaging for analyte sensorsystem 308) and may thus trigger a false wakeup of analyte sensor system308. The relationship between humidity/moisture and certain measurableelectrical characteristics of analyte sensor 10 (e.g. impedance,capacitance, etc.) may thus be exploited to more accurately detectanalyte sensor 10 insertion events and, in response, activate analytesensor system 308.

For example, under lower humidity conditions (e.g., 90% RH) impedancemay be relatively high (e.g., 10 MΩ). Upon analyte sensor 10 beingimplanted, however, impedance can decrease, in some cases relativelyquickly (e.g., to several hundred kΩ). Accordingly, in embodiments, achange, rate of change, and/or threshold impedance value (e.g., ofapproximately 300 to 500 kΩ by way of specific but non-limitingillustration) can be used to distinguish between high humidityconditions that may occur in a non-insertion environment outside ahost's body, on the one hand, and moisture conditions that may occur inrelation to analyte sensor 10 being implanted within the host's body, onthe other hand. This may help to prevent (or resist) environmentalconditions from triggering analyte sensor system 308 to activate or exita lower power state when doing so is not desired. The desired level forthe impedance threshold can be based on the time that may be allottedfor the wakeup trigger time window for analyte sensor system 308 afterinsertion of analyte sensor 10, which may be a trade-off made againststate robustness to false wakeup from, for example, noise, signalmagnitude, circuit measurement inaccuracies, etc. Examples of feasiblewake up trigger times include but are not limited to approximately 30seconds or less to approximately 60 seconds or more.

As shown in FIG. 7C, at hydration 736 (e.g., in units of %) prior toimplantation of analyte sensor system 10, point 740 of plot 734corresponds to impedance value 738 (e.g., in Ω). Additionally, athydration 756 following implantation of analyte sensor 10, point 760corresponds to impedance value 758. In embodiments, impedance value 758may be distinctly lower than impedance value 738, such that a range ofimpedance values between impedance value 744 and impedance value 750,corresponding respectively to points 746 and 752 on plot 734, may beused as thresholds for detecting implantation of analyte sensor 10 andmay thus be used to trigger analyte sensor system 308 to activate and/orexit a lower power state. In additional or other examples, a gradient orderivative of impedance value as a function of hydration can bemonitored to detect analyte sensor 10 implantation. Thus, for example,the impedance of analyte sensor 10 can be monitored, and when theimpedance crosses a threshold value for impedance (e.g., or meets athreshold derivative, gradient, or other condition), activation or achange of state of analyte sensor system 308 can be triggered. In aspecific example, analyte sensor 10 may have an impedance associatedtherewith of approximately 10 MΩ before insertion of analyte sensor 10,at a relatively lower hydration value (e.g., within a range of valuestypical for environmental humidity outside a host's body or in a certainenvironment). Then, the impedance value of analyte sensor 10 may drop toapproximately 100 kΩ as hydration increases after analyte sensor 10 isinserted into a user's body.

The impedance associated with analyte sensor 10 may be measured usingvarious techniques, including, for example, using a voltage or currentstep or other function, etc., using electro chemical impedancespectroscopy (e.g., as described in U.S. Pat. No. 9,801,575, thecontents of which are hereby incorporated by reference in theirentirety), or using any other known method. By way of example,activation detection circuit 520 may include a driver circuit (e.g.,function generator, oscillator, or the like) operation to generate thestep function or other function or signal that may be used for measuringanalyte sensor 10 impedance. For example, as the voltage associated withthe step function or other signal is applied to analyte sensor 10, aresulting current between terminals of analyte sensor 10 can be detectedusing activation detection circuit 520. In example implementations, therelationship between the applied voltage and resulting current can thenbe used to calculate an impedance for analyte sensor 10.

Generally, to reduce/minimize battery power usage and avoid sending morecurrent through analyte sensor 10 than is necessary or appropriate, anyimpedance measurement done for activation purposes should use arelatively low amplitude waveform (e.g., less than approximately 50 mV)and preferably zero net current (e.g., centered around 0 V of electrodevoltage bias). In embodiments, as mentioned above, measurementsindicative of impedance can be characterized using activation detectioncircuit 520 through applying a voltage (e.g., step function) to analytesensor 10. The magnitude of the resulting current flow (which, e.g., mayinclude a current spike) may be inversely related to an impedance of themembrane of analyte sensor 10. Thus, using Ohm's law, for example andnot limitation, the impedance may be determined by monitoring voltages,currents, and/or digital counts of either or both.

Activation detection circuit 520 may include circuitry to detect whetherthe impedance is above or below a set level. Such circuitry will bediscussed in further detail below in connection with at least FIGS. 8Aand 12-14. Regarding FIG. 8A, at a high level, the circuitry can capturepositive current spikes using a switch that may be driven using avoltage source that may apply, for example, a square wave or otherwaveform to analyte sensor 10. The positive currents may then be used tocharge a capacitor. The voltage that may develop over the capacitor mayrepresent a measure of the impedance of analyte sensor 10 (e.g., asmeasured based on a voltage divider that may be arranged between animpedance of analyte sensor 10 and a known impedance). By using avoltage comparator circuit set at a desired level, insertion of analytesensor 10 can be determined and used to trigger analyte sensor system308 to exit a lower power state. Such circuits may be designed andintegrated into a chip that can be operated at very low power (e.g.,less than 1 uA during lower power state). Upon detecting implantation ofanalyte sensor 10, the chip and/or circuit can then send a controlsignal to processor 535 to cause analyte sensor system 308 to exit thelower power state.

In embodiments, voltage to current amplifiers and additional switchesmay be used to decouple analyte sensor 10 from a detection circuit afteranalyte sensor system 308 exits the lower power state. It should also benoted that at high humidity conditions (e.g., such as may occur duringstorage), the net current through analyte sensor 10 may be limited. Thiscan provide an advantage over techniques for activation of analytesensor system 308 that apply a fixed bias to analyte sensor 10 (e.g., avoltage, such as 0.6 V). When such techniques are used, under highhumidity conditions, current that flows through analyte sensor 10 as aresult of the application of the fixed bias may consume an undesirableamount of power and/or may impact the performance of analyte sensor 10.

Turning now to FIG. 8A, an example activation detection circuit 800 isshown, in accordance with embodiments of the present disclosure. Circuit800 may be used, for example, to detect current in a lower power wakeupcircuit that can be used for activating analyte sensor system 308. At ahigh level, and with reference to FIG. 5 by way of example and contextfor certain embodiments, circuit 800 can use an inrush (e.g., charging)current through a capacitance of analyte sensor 530 to generate voltagepulses. The voltage pulses may be monitored by a detection circuit and,if the pulses satisfy one or more conditions, analyte sensor system 308may be triggered to exit a lower power state. By way of example, incertain embodiments, a predetermined number of pulses exceeding avoltage threshold may trigger activation of analyte sensor system 308.Additional examples are described below.

Components such as one or more switches and one or more current limitingresistors may be used in circuit 800 to provide a more accuratelydetectable analyte sensor 530 implantation event and thus more robustcontrol for activating analyte sensor system 308 or causing analytesensor system 308 to exit a lower power mode. For example, at a firsttime, a switch can be used to couple a first terminal of analyte sensor530 to a potentiostat or other measurement device or circuit. Adetection circuit may in certain examples include an amplifying element(such as, e.g., a comparator, low-noise amplifier, other amplifier, orthe like) and/or other circuitry. The detection circuit can be used todetect whether a voltage generated using circuit 800, for example, basedon (e.g., charging) current that may flow through capacitance of analytesensor 530, exceeds a threshold or otherwise meets one or moreconditions. If the voltage exceeds or otherwise meets the condition(s),activation of analyte sensor system 308 can be triggered. For example,such a voltage can be generated using a current-to-voltage conversioneffect of components that may be included in or used by circuit 800,such as capacitor 834, switch element 818, and/or driver circuit 806.

And, for example, at a second time, the switch that may be used tocouple the first terminal of analyte sensor 530 to the measurementdevice (e.g., potentiostat) can be opened or put in a high impedancestate, to decouple the first terminal of analyte sensor 530 from themeasurement device/potentiostat, while a second switch can couple thefirst and second terminals of analyte sensor 530 together, for example,through a current limiting resistor, to at least substantially dischargeanalyte sensor 530 capacitance. In this manner the voltage potentialthat may be present across analyte sensor 530 can be set, reset, and/orzeroed out. This can effectively reset the circuit so that the chargingcurrent inrush event through analyte sensor 530 capacitance can berepeated, thus enabling another detectable event and providing a morerobust activation detection mechanism for analyte sensor system 308. Insome instances, this activation detection mechanism can more reliablydistinguish between multiple electrical characteristics that may bemeasured for analyte sensor 530, where some such electricalcharacteristics may be indicative of a hydration state of analyte sensor530 and other such characteristics may merely indicate a high humidityenvironment, and activate analyte sensor system 308 more appropriately,reliably, or accurately.

More specifically, FIG. 8A shows that circuit 800 may include analytesensor 808 and measurement device 810 (e.g., a potentiostat). It will beappreciated by one of skill upon studying the present disclosure that incertain embodiments analyte sensor 808 may be similar, substantiallysimilar, or the same as, for example, analyte sensor 530 referenced inconnection with FIG. 5. In certain embodiments, analyte sensor 808 maybe at least partially different than analyte sensor 530, depending uponthe contexts and/or applications in which analyte sensors 530 and/or 808may be used. Measurement device 810 may be used to apply a bias toanalyte sensor 808 and/or to gather information from analyte sensor 808that can be used to calculate a level of an analyte in a host into whomanalyte sensor 808 has been implanted.

In addition, circuit 800 may include capacitive element 834, andoptionally includes resistive element 832. Circuit 800 may also includedetection circuit 802, which may in some cases be, use, or include anamplifying element (e.g., a comparator), for example. Additionally,circuit 800 may include one or more of reference voltage 804, referencevoltage 818, and driver circuit 806, which may be, for example, aclock-based driver. It should be appreciated that one or more ofreference voltages 804 and 818 may be substituted for other referencesignals. It should also be appreciated that driver circuit 806 may bedriven by signals other than clock signals.

In embodiments, current based activation techniques for analyte sensorsystem 308 may be performed using a circuit similar to circuit 800 shownin FIG. 8A. However, certain modifications may be made in connectionwith some such embodiments. For example, switch element 812 may not bepresent in circuit 800, or may be bypassed or short circuited, forexample. Switch element 814 may also not be present or may beeffectively removed from circuit 800, and/or may be placed in a highimpedance or open circuit state. In such cases, resistive element 832may also be effectively removed from circuit 800. It should beappreciated that other means may be employed to effectively removeand/or bypass resistive element 832. In embodiments, implantation ofanalyte sensor 808 may still be determined/monitored based upondetecting certain (e.g., sufficient) current flow(s) between first andsecond terminals 828 and 830 of analyte sensor 808.

Example features of such a modified or similar version of circuit 800are now provided, as follows. Measurement device 810 may apply apotential across terminals 828 and 830 of analyte sensor 830 (e.g., asubstantially continual voltage). For example, terminal 828 may beplaced at a higher potential than terminal 830, such that current flowthrough analyte sensor 808 may be sourced through terminal 824 ofmeasurement device 810 (e.g., a potentiostat in some cases).Additionally, for example, terminal 826 of measurement device 810 andterminal 830 of analyte sensor 808 may be coupled to one another and/orto current-to-voltage conversion circuitry.

In embodiments, the current-to-voltage conversion circuitry may includecapacitive element 834 that may be coupled at a first end to terminals826 and 830, and at a second end to reference voltage 818 (e.g.,ground). The first end of capacitive element may also be coupled toswitching element 816. Switching element 816 may be driven by drivingcircuit 806, which may be, include, and/or use a clock-based or othersignal type driver. Switching element 816 may in this manner causeterminals 826 and 830 to be alternatively coupled to and decoupled fromreference voltage 818. Terminals 826 and 830 may be coupled to anddecoupled from reference voltage 818 periodically according to aconfigurable, programmable, adaptable, and/or variableinterval/frequency (e.g., 10 Hz). In some cases, driver circuit 806 maycause the coupling/decoupling of terminals 826 and 830 to/from referencevoltage 818 to be aperiodic, asynchronous, and/or event-driven.

In one example, when switch element 816 is placed in a higher impedancestate or is open, for example at a first time, terminals 826 and 830 maybe disconnected or decoupled from reference voltage 818 (e.g., may befloating). Thus, current flowing through a capacitance of analyte sensor808 may effectively be delivered to capacitive element 834 as chargingcurrent. The charging current in turn may cause a voltage potential todevelop across capacitive element 834. When switch element 816 is placedin a lower impedance or conductive state or is closed, for example at asecond time, terminals 826 and 830 may be connected or coupled, in somecases directly, to reference voltage 818 (e.g., ground). In thisconfiguration, the charge that may be stored in capacitive element 834may be at least substantially discharged (e.g., to ground), such thatthe voltage potential that may have developed across capacitive element834 may be returned/reset to at least close to the potential ofreference voltage 818 (e.g., ground or 0 V). Accordingly, in thisexample, when current flows through capacitance of analyte sensor 808,due to the action of switch element 816, the resultant voltage signalwaveform that may be present at terminals 826 and 830 may represent aseries of voltage pulses (e.g., voltages across capacitive element 834as a function of time), where such pulses may be proportional to amagnitude of current flow through the capacitance of analyte sensor 808.

Continuing the example, in circuit 800, input 822 of detection circuit802 (e.g., a voltage detection circuit, which may be implemented as anamplifying element, comparator, other circuitry, or the like) may becoupled to terminals 826 and 830. In embodiments, detection circuit 802is operable to compare the voltage across capacitive element 834 toreference voltage 804, which may be configurable, programmable,variable, adaptable, etc. Detection circuit 802 may be further operableto produce output 836 that may be used to trigger activation of, e.g.,analyte sensor system 308, if certain condition(s) are met (e.g., if thevoltage across capacitive element 834 is above, below, or within a rangeof reference voltage 804, or is exhibiting a particular trend, etc.). Itshould be noted that reference voltage 804 can be configured based oncalibration, can be set according to a predeterminedvalue/characteristic, and/or can be configured on the fly or based onenvironmental conditions experienced by analyte sensor system 308 in thefield. Moreover, detection circuit 802 may include and/or useconfigurable digital logic circuitry (not shown in FIG. 8A) operable tocount and/or otherwise characterize or measure a number of sequentialvoltage pulses that may satisfy (e.g., meet or exceed) a threshold. Forexample, if the number and/or characterization of measured/monitoredpulses satisfies a configurable condition (e.g., thresholdnumber/magnitude), output 836 may indicate that analyte sensor system308 should be activated or caused or triggered to exit a lower powerstate.

In certain cases, however, the above-described example may be moreparticularly suited for use in conjunction with certain electricalmodels of analyte sensor 808. For example, the above-described examplecircuit may be more suited to implementations where analyte sensor 808is modeled as a substantially or purely resistive load between terminals828 and 830 of analyte sensor 808. But, for certain examples, thissubstantially resistive load may not be an approximate representation ofanalyte sensor 808. By way of illustration, in the case of asubstantially or purely resistive load, the voltage pulses that maydevelop across capacitive element 834 as a result of charging currentmay be of a substantially constant amplitude for a given substantiallyconstant current. Therefore, the amplitude of the voltage pulses mayincrease proportionally with increasing current.

As described above in connection with FIG. 7A, however, in embodiments,the electrical behavior of analyte sensor 808 may not be as accuratelymodeled by a substantially or purely resistive load. Instead, it may bemore accurate to electrically model analyte sensor 808 using a morecomplex passive circuit model, for example, as is shown in FIG. 7A, thatincludes both capacitors and resistors and that may include otherelements. For example, when the relatively larger capacitance Cdoublelayer 718 of analyte sensor 808 is included in the electrical model thatmay be employed, circuit 800 may operate in a different fashion whenterminals 828 and 830 of analyte sensor 808 are first connected withincircuit 800. In some cases, the difference may be significant orappreciable. By way of illustration, instead of a constant amplitudevoltage pulse sequence or train that may result when the resistivemodel/load is employed (e.g., as describe in connection with the aboveexample), the waveform characteristic for the voltage across capacitiveelement 834 may be substantially affected (and in some cases dominated)by the initial inrush of charging current that may flow through thecapacitance of analyte sensor 808. This may result in (e.g., a series)of voltage pulses that initially have a larger amplitude and thensubsequently have a decreasing amplitude. The amplitude may decreaserapidly in some cases, and may decrease substantially, for example,according to an exponential decay that may be associated with aresistive/capacitive (RC) characteristic of the electrical equivalentmodel for analyte sensor 808 illustrated by way of example in FIG. 7A.Here, reference is made by way of example to FIG. 8B, which is discussedin further detail below. As shown in FIG. 8B, for example, the pulsesthat may be included in waveform 870 exhibit an exponential decay duringtime period 845. It should be appreciated, however, that if theresistive model is used for analyte sensor 808, this decay may not bepresent, and instead, the pulses of waveform 870 may be relativelyconstant in amplitude.

Furthermore, once the capacitance of analyte sensor 808 is charged andthe currently flow is primarily due to steady state current, theoperation of the current-to-voltage circuit may remain significantlyaffected by the presence of the charged capacitor. For example, if amore complex electrical model is used, the amplitude of the residualvoltage pulses that may be measurable across capacitive element 834 fora given steady state current may be meaningfully lower than theequivalent steady state current that would be present under theresistive load electrical model for analyte sensor 808. Moreover, theproportional difference in magnitude of the corresponding voltagewaveforms for the two different currents may no longer be sufficientlydifferentiated by detection circuit 802 under normal circumstances. Forexample, detection circuit 802 may not be capable of as accuratelydetecting threshold crossings etc., due to the relatively small ordiminished difference in the steady state voltage pulse amplitude thatmay result when the electrical model of FIG. 7A is employed.

Accordingly, in view of the above, it should be appreciated that theexample configuration of circuit 800 described above may produce steadystate currents that may not result in voltage pulse waveforms ofsufficient magnitude for detection or differentiation by detectioncircuit 802. This example configuration of circuit 800 may thus not beas conducive to accurate and robust activation of analyte sensor system308. For example, there may be only a single or small number ofopportunities to generate a sufficient voltage waveform that can be moreeasily/accurately/reliably detected by detection circuit 802. Forinstance, the initial relatively large voltage pulse that may resultfrom initial inrush of charging current may provide only a singledetection event. And if this initial relatively large pulse or pulsesare not detected by detection circuit 802 or analyte sensor system 308is not activated as a result of the initial pulse(s) (e.g., becauseanalyte sensor 808 may not be sufficiently hydrated at time ofconnection to circuit 800), circuit 800 may not have anothersufficiently detectable opportunity to detect/assess implantation ofanalyte sensor 808.

Accordingly, embodiments of the present disclosure include aconfiguration of circuit 800 that is resettable by virtue of circuitcomponents such as switches and other elements. For example, referringfurther to FIG. 8A, circuit 800 may include switch elements 812 and 814.Switch elements 812, 814, and 816 may be implemented using electricalcomponents, including discrete or integrated components, such astransistors or other passive/active devices (e.g., FET switches, etc.).As will be discussed below in further detail, switch elements 812 and814 may be complementary, such that when one switch element is closed,the other may be open and vice versa. Switch elements 812 and 814 may becontrolled using a clock or other signal driver, and in some cases thisclock may be derived from the clock or other source/driving signal usedfor driver circuit 806. In embodiments, switch elements 812 and 814 maybe controlled by a clock or other source with a lower frequency than theclock or other source that may be used for driver circuit 806. Forexample, the (e.g., clock) frequency for switch elements 812 and 814 maybe a fraction of the (e.g., clock) frequency for switching element 816,where the value of the fraction that may be used can be configurable,programmable, adaptable, and/or variable. Examples/options for thefraction may include, in some cases, 1/10, 1/20, /40, 1/80 etc. Thus,per these examples/options, switch elements 812 and 814 may change stateevery 10, 20, 40, or 80 cycles of the clock for switch element 816.Other ratios and relationships that can be set up with respect to drivercircuit 806 and the control of switch elements 812 and 814 will beappreciated upon studying the present disclosure.

Output 836 of detection circuit 802 may be coupled to, for example,processor 535 of analyte sensor system 308, such that output 836 may beused for activation or triggering of analyte sensor system 308. Circuit800 may be implemented within or in conjunction with activationdetection circuit 520. When circuit 800 is implemented as or as part ofactivation detection circuit 520, output 836 may be coupled to processor535, such that when signaled to do so, processor 535 may be used tocause or trigger analyte sensor system 308 to wake up or exit a lowerpower state. As alluded to above, analyte sensor 808 may include firstand second terminals 828 and 830. Detection circuit 802 may includereference terminal 820 and input terminal 822. Measurement device 810may include first terminal 824 and second terminal 826.

As mentioned, circuit 800 may be used to control activation of analytesensor system 308. Detection circuit 802 may indicate whether a signalat input terminal 822 meets one or more conditions. For example, thecondition may be or include one or more threshold voltages that may beset using reference voltage(s) 804 applied to reference terminal(s) 820of detection circuit 802. The voltage(s) at input terminal(s) 822 may beindicative of a current that may flow between first and second terminals828 and 830 of analyte sensor 808 (e.g., as described above, circuitelements of circuit 800, including capacitive element 834, may be usedto effectively convert current through analyte sensor 808 to a voltage).For example, the condition(s) may be, use, and/or include a thresholdthat is programmable, adaptable, variable, and/or configurable, etc.

In certain instances, the condition(s) can be configured such that thecondition(s) may be met when the voltage(s) of one or more signalsprovided at input terminal 822 is (are) indicative of current that mayflow between first and second terminals 828 and 830 of analyte sensor808 when analyte sensor 808 is implanted in a host or under otherconditions. In such cases, output(s) 836 of detection circuit 802 may beused to trigger analyte sensor system 308 to exit a lower power state byindicating that this signal(s) at input terminal 822 satisfies(y) thecondition(s) (e.g., depending on the level(s) of the output signal(s)836). For example, in some cases, output(s) 836 of detection circuit 802may include binary levels, multiple discrete levels, and/or continuousor substantially continuous or analog values that may be used to triggeractivation of analyte sensor system 308 into one or more triggered oractive states. In some cases, the state that analyte sensor system 308enters may depend upon characteristics (e.g., levels, trends, etc.) ofoutput 836. In embodiments, the condition(s) may be configured to be metwhen a certain number of voltage pulses satisfy (e.g., meet or exceed)the threshold(s), or when a certain number of sets of voltage pulsesexceed the threshold(s), as will be discussed further in connection withFIG. 8B.

Switch element 812 may be used to couple or decouple first terminal 828of analyte sensor 808 to/from first terminal 824 of measurement device810 (e.g., a potentiostat). Switch element 814 may be used to couple ordecouple first terminal 828 of analyte sensor 808 to/from input terminal822 of detection circuit 802 (optionally through resistive element 832).Input terminal 822 of detection circuit 802 may be coupled to secondterminal 830 of analyte sensor 808 and to second terminal 826 ofmeasurement device 810.

At a first time, switch element 812 may be closed or placed in aconductive state, coupling first terminal 828 of analyte sensor 808 tofirst terminal 824 of measurement device 810. Switch element 814 may beopen or placed in a high impedance state at this time, decoupling inputterminal 822 of detection circuit 802 from first terminal 828 of analytesensor 808. Thus, at the first time, measurement device 810 may be usedin connection with gathering information that may be used to calculatethe level of the analyte in the host. Furthermore, a voltage waveformgenerated using circuit 800 (e.g., as alluded to above), andspecifically using charging current that may flow through a capacitanceof analyte sensor 808, may be fed to the terminal 822 and monitored andcompared to reference voltage 804 using detection circuit 802 (e.g.,which may be or include an amplifying element and/or a comparator orother circuit).

At a second time, switch element 812 may be open or set to a highimpedance state, thus decoupling first terminal 828 of analyte sensor808 from first terminal 824 of measurement device 810. Switch element814 may be closed or set to a low impedance or conductive state at thistime, thus coupling second terminal 830 of analyte sensor 808 to firstterminal 828 of analyte sensor 808 (optionally through resistive element832 in some cases). This may reduce or possibly eliminate the voltagepotential present across analyte sensor 808 and at least substantiallydischarge the stored charge of a capacitance of analyte sensor 808 (see,e.g., FIG. 7A) using a switching action of driver 806 and switch element816 to create a conductive path to reference voltage 818. As mentioned,resistive element 832 may optionally be used to limit current that mayflow through switch elements 814 and/or 816 when switch elements 814and/or 816 is/are closed or placed in a conductive or low impedancestate.

Capacitive element 834 may be coupled between input terminal 822 ofdetection circuit 802 (which is shown in this example as being coupledto second terminal 830 of analyte sensor 808) and voltage reference 818(e.g., ground). Switch element 816 may be driven by, or otherwise obtainas an input, a signal from driver circuit 806 (e.g., a clock or othersignal), such that switch element 816 may periodically couple inputterminal 822 of detection circuit 802 to reference 818. Where, forexample, voltage reference 818 is ground, this may at leastsubstantially discharge capacitive element 834, as furtherreferenced/discussed in connection with FIG. 8B. As mentioned,capacitive element 834 in conjunction with driver circuit 806 and/orswitch element 816 may be used to implement a current-to-voltagecircuit. The current-to-voltage circuit may be operable to convertcurrent that may flow through analyte sensor 808 into a voltage (e.g.,waveform) that can be measured or otherwise characterized usingdetection circuit 802 in connection with determining whether athreshold/condition has been met or satisfied, as referenced above, andfurther in connection with activating and/or triggering analyte sensorsystem 308 to change states.

In embodiments, switch elements 812 and 814 may be driven by a commonsignal that may be inverted for one of either switch element 812 orswitch element 814. Alternatively, switch elements 812 and 814 may bedriven by a common signal but the devices used for switches 812 and 814may have opposite polarities. For example, in embodiments, switchelements 812 and 814 may be driven such that they are configured to bein opposite (e.g., impedance) states at a given time. Thus, switchelements 812 and 814 may be configured such that in large part, whenswitch element 812 is closed, switch element 814 will be open, and viceversa. Configured in this manner, switch elements 812 and 814 can beused to at least substantially discharge a capacitance associated withanalyte sensor 808. As such, the initial inrush of current through thecapacitance of analyte sensor 808 that may typically be associated withimplantation of analyte sensor 808 into a host's body can be largelyrecreated and used to generate additional voltage pulses that may bemonitored for purposes of activating analyte sensor system 308 and/orcausing the same to exit a lower power state. Thus, in the situationwhen the current rush resulting from implantation of analyte sensor 808does not trigger activation, switch elements 812 and 814 can be used toeffectively reset circuit 800 so that another monitorable current rushmay occur and be used to trigger activation of analyte sensor system308.

Additionally/alternatively, to allow for flexibility, tuning,configuration, and/or optimization, the timing for controlling switchelements 812 and 814 to be in different states may predetermined,programmable, adaptable, variable, and/or configurable, such that switchelements 812 and/or 814 may be placed in particular states/modes inaccordance with various durations/intervals/frequencies/etc. and/or aduty cycles and the like. Such timing control may be implemented usingand/or derived from driver circuit 806, such that, for example, everygiven number of cycles of driver circuit 806, the state of switchelements 812 and 814 can change and/or be maintained for aselectable/controllable duration.

FIG. 8B illustrates an example plot of an analyte sensor 808 signal(e.g., voltage, current, etc.) according to embodiments of thedisclosure. Waveforms 870 and 880 may represent signals (e.g., voltages,current, etc.) 840 as a function of time 842 (e.g., in seconds), wheresuch signals may be those present on or fed to input terminal 822 ofdetection circuit 802 in circuit 800 (referencing FIG. 8A by way ofexample). Reference voltage 848 may be set such that when a voltage orother signal present on input terminal 822 of detection circuit 802meets, exceeds, or crosses reference voltage 848, output 836 ofdetection circuit 802 can be used to trigger activation of analytesensor system 308, as mentioned above. As shown in FIG. 8B, during thetime between the end of waveform 870 and the beginning of waveform 880,the signal (e.g., voltage) on input terminal 822 of detection circuit802 may have been at least substantially discharged or reset by, amongother things, switch element 814 and/or switch element 816 being closed.Resetting the voltage across analyte sensor 808 can enable circuit 800to monitor additional detection events in which the voltage on inputterminal 822 may cross, meet, or exceed reference voltage 848.

As shown in FIG. 8B, waveform 870 may include pulses 844 a, 844 b, and844 c, and as shown can include additional pulses (including pulses notexplicitly illustrated). By way of non-limiting example, driver circuit806 may provide a clock (e.g., square wave, sine wave, etc.) or othersignal for driving switch element 816. The period of the clock signalmay be thought of as the spacing between each of pulses 844 a, 844 b,and 844 c. In certain examples, driver circuit 806 may provide anaperiodic, asynchronous, and/or event-driven signal for controlling theoperation of switch element 816.

By way of non-limiting example, waveform 870 may have a duration of acertain time period 845, which may in some cases be approximately onesecond, and the period of the clock signal from driver circuit 806 maybe approximately 100 msec. As further illustrated, after the initialcurrent rush and corresponding (e.g., voltage) pulse 844 a of waveform870 that may result in connection with implantation of analyte sensor808 into a host, each successive pulse 844 b, 844 c, etc. may decreasein amplitude, for example, according to a decay profile that may beassociated with an effective time constant (e.g., RC time constant, asdescribed above) of analyte sensor 808. Hence, as described above,switch elements 812 and 814 may be used to largely recreate the initialcurrent rush used to form a pulse with a certain magnitude (e.g., pulse844 a). This is shown for example by waveform 880, which may includepulses 846 a, 846 b, 846 c, etc.

When switch elements 812 and 814 are set in the fashion described above,waveform 870 may drop to or near ground or another reference voltage, asrepresented at time period 855. In embodiments, time period 855 may beapproximately one second (e.g., or any other amount of time that isapproximately and/or sufficiently long enough to substantially and/orfully discharge the capacitance of analyte sensor 808), after whichwaveform 880 and pulse 846 a can be measured according to the states ofswitch elements 812 and 814. Waveform 880 may then be monitored in theabove-described manner for activating analyte sensor system 308.

With respect to the one or more conditions that may be used foractivating analyte sensor system 308 in connection with circuit 800,many variations are contemplated in connection with the presentdisclosure. For example, a single pulse, such as pulse 844 a, meeting,exceeding, and/or crossing threshold 848 or otherwise satisfying acondition may trigger activation of analyte sensor system 308. Inembodiments, a predefined number of pulses 844 a, 844 b, 844 c meeting,exceeding, and/or crossing threshold 848 or otherwise satisfying acondition may trigger activation. In some cases, a certain number ofpulses from more than one waveform (e.g. waveform 870, 880, etc.), ordifferent respective numbers of pulses (e.g., 844 a, 844 b, etc., and846 a, 846 b, etc.) for each waveform 870, 880 may be used fortriggering activation. In certain examples, if the number of pulses fromwaveform 870 that meet a condition does not result in activation, one ormore pulses from waveform 880 may be monitored for activation purposes.In some cases, a certain number of pulses exceeding threshold 848 by acertain amount may trigger activation of analyte sensor system 308. Inembodiments, if a first condition is not met in connection withdetection circuit measuring pulses of waveform 870, a second (e.g.,modified) condition may be used for monitoring pulses of waveform 880.

In embodiments, if analyte sensor system 308 is activated and/ortriggered to exit a lower power state in response to waveform 870,waveform 880 may in certain cases not need to be generated. In othercases, more than one waveform 870, 880, etc. may be used for activationspurposes, and subsequent waveforms other than waveforms 870, 880 (notshown in FIG. 8B) may not need to be generated. In some cases, ifanalyte sensor 308 is not activated in response to at least one ofwaveforms 870, 880, etc., additional waveforms may continually begenerated. In embodiments, after a configurable number of waveforms havebeen generated without analyte sensor system 308 being activated,waveform generation may be at least temporarily suspended, including insome cases for a predetermined, configurable, and/or event-based amountof time. Accordingly, in certain embodiments, the ability to essentiallyreset circuit 800 can enable more robust activation detection schemes asdiscussed above/herein.

Additionally, with further reference to FIG. 8B, in certain embodiments,the respective durations of time periods 845, 855, and 865 may be variedtogether or independently. For example, time periods 845 and 865 may bethought of as an active (e.g., default) state, and time period 855 maybe thought of as a reset or inactive state with respect to thegeneration of pulses. In examples, the duration or duty cycle of theactive state (e.g., during time periods 845 and/or 865) and the resetstate (e.g., during time period 855) may be configurable, including onthe fly. In some cases, the duty cycle may be configured to be offset,such that circuit 800 may remain in the reset state longer than in theactive state or vice versa.

For example, it may be beneficial in some circumstances to increase theduration of the reset cycle relative to the active state. This maybetter provide the capacitance of analyte sensor 808 sufficient time tomore fully discharge between two successive active cycles (e.g., betweenthe end of time period 845 and the beginning of time period 865). Thismay facilitate a more consistent, repeatable, and/or accuratelydetectable initial charging current response and corresponding voltagepulse waveform. Here, it should be noted that any number of waveforms870, 880 may be repeated in the context of FIG. 8B. The length of resetstates between various such waveforms may be varied, for example, asbetween two sets waveforms associated with active states. In some cases,the length of the reset state(s) may be configurable, variable,adaptable, and/or programmable, for example, the length may be changedin response to detection circuit 802 not triggering activation ofanalyte sensor system 308 after a certain amount of time has passedand/or under the presence of other conditions that may be monitoredusing analyte sensor system 308 as described herein (e.g., accelerometeror hydration related conditions). Additionally, the length of the active(or reset) states may be varied from active state to active state (orreset state to reset state), or on any other basis.

In one example, when switch element 812 is closed and switch element 814is open, circuit 800 may be in the active state. When switch element 814is closed and switch element 812 is open, circuit 800 may be in thereset state. In the reset state, in this example, analyte sensor 808 maybe disconnected/decoupled from terminal 824. As such, there may be nopower applied to analyte sensor 808. At the same time, switch element814, upon being closed, may connect/couple terminals 828 and 830 to oneanother, optionally via resistive element 832 (e.g., which may act as acurrent limiter). In this manner, the charge that may be stored in thecapacitance of analyte sensor 808 may be at least substantiallydischarged by the path that may be created by switch element 814 andoptionally resistive element 832 in conjunction with thecontinued/ongoing toggling of switch element 816 that can be used tocoupled terminal 828 to reference voltage 818 (e.g., ground) throughthis path. The charge that may be stored in capacitive element 834 canalso be at least substantially discharged under these conditions (e.g.,during this time period) because, where terminal 824 of measurementdevice 810 has been decoupled from the remaining elements of circuit800, there is no new source of charging current for capacitive element834.

Advantageously, circuit 800 when employed in conjunction with thecircuit model shown in FIG. 7A or the like may result in arepeatable/consistent and/or controllable/configurable opportunity togenerate voltage waveform(s) (e.g., waveforms 870 and 880, referencingFIG. 8B) that are sufficiently, reliably, and/or accurately detectableusing detection circuit 802. If the initial current rush is not detectedby analyte system 308 using circuit 800, due to any number ofcircumstances that may be present (e.g., analyte sensor 808 is notsufficiently hydrated, etc.), circuit 800 may enable additionalattempts/chances for detection circuit 802 to detect analyte sensor 808during subsequent active cycles following the reset cycle(s) that may beaffected in the above-described manner.

FIG. 8C is an operational flow diagram illustrating method 850 forcontrolling activation of analyte sensor system 308 in accordance withembodiments of the disclosure. Method 850 is described below withreference to certain circuit diagram elements illustrated and discussedin connection with FIG. 8A, but method 850 should not be understood tonecessarily be limited to such configurations/elements. Operations ofmethod 850 may be employed in connection with a robust activation schemefor analyte sensor system 308.

At operation 852, method 850 may involve detection circuit 802monitoring analyte sensor 808, for example, monitoring a voltage presenton input terminal 822 of detection unit 802, where input terminal 822may be coupled to second terminal 830 of analyte sensor 808. Analytesensor 808 may be coupled to measurement device 810 (e.g., apotentiostat or other measurement circuit) for monitoring electricalproperties of analyte sensor 808. Method 850 may optionally include, atoperation 854, using switch element 816 to couple input terminal 822 ofdetection circuit 802 to reference voltage 818 (e.g., ground). Switchelement 816 may be controlled and/or driven using one or more signalsfrom driver circuit 806 (e.g., a clock or other signal driver).

At operation 860, method 850 may involve determining if the measurementsof input terminal 822 of detection circuit 802 satisfy one or moreconditions. For example, such conditions may include whether inputterminal 822 of detection circuit 802 meets, exceeds, or crosses athreshold voltage (e.g., threshold 848, with reference to FIG. 8B, byway of example) or meets another characteristic, such as satisfyingthreshold 848 a number of times, or multiple times across multipledifferent time periods (e.g., as described above in connection with FIG.8B). In embodiments, the condition/characteristic may include aconsistent frequency of positive determinations that input terminal 822of detection circuit 802 presents a voltage that meets, exceeds, orcrosses a threshold voltage or meets another condition over a durationof time, thus helping ensure that the condition is not reached based onan anomaly.

By way of illustration, operation 860 may entail a voltage at inputterminal 822 of detection circuit being compared to a threshold value(e.g., reference voltage 804, referencing FIG. 8A by way of example).For example, the voltage at input terminal 822 of detection circuit 802may be indicative of a current that may flow between first and secondterminals 828 and 830 of analyte sensor 808. As discussed above, incertain examples, detection circuit 802 may be, use, and/or include anamplifying element, comparator, and/or the like that can be used todetect whether the measured voltage across terminals 828 and 830 ofanalyte sensor 808 may meet or satisfy a characteristic (e.g., exceeds athreshold value). In embodiments, the characteristic (e.g., thresholdvoltage) may be set using reference voltage 804 that may be applied toreference terminal 820 of detection circuit 802.

If the one or more conditions are satisfied, method 850 may furtherinclude, at operation 862, analyte sensor system 308 being triggered toexit a lower power state. For example, analyte sensor system 308 may betriggered to exit the lower power state as a result of the one or moreconditions being satisfied, as determined using circuit 800 andindicated by output 836 (referencing FIG. 8A by way of example). If theone or more conditions are not satisfied, however, method 850 mayinclude operation 858, which entails controlling switch elements 812 and814 (e.g., as described above in connection with FIGS. 8A and 8B) to atleast substantially discharge a capacitance associated with analytesensor 808. Method 850 may then entail returning to operation 852, whileanalyte sensor system 308 remains in the lower power state.

Thus, operation 858 may involve causing switch elements 812 and 814 toperiodically at least substantially discharge a capacitance of analytesensor 808, where, at a first time, switch 812 can be effectively closedor put into a low impedance state and thus be used to couple firstterminal 828 of analyte sensor 808 to measurement device 810. And at asecond time, switch element 812 may effectively be opened or put into ahigh impedance state in order to largely decouple first terminal 828 ofanalyte sensor 808 from measurement device 810, while switch element 814can couple first terminal 828 and second terminal 830 of analyte sensor808 together (e.g., in some cases through resistive element 834 that maybe used as a current limiter) to at least substantially dischargeanalyte sensor 808 and/or circuit 800 capacitance. As discussed above,operation 858 can effectively reset circuit 800 to a measurement stateso that a current that may flow through a capacitance of analyte sensor808 can be largely repeated, thus enabling another detectable event andproviding a more robust activation detection mechanism for analytesensor system 308.

With further reference to FIG. 5, another technique that may be used forpurposes of activating analyte sensor system 308 is voltage generation.In embodiments, a transcutaneous portion of analyte sensor 530 may beused to electrochemically generate a small voltage. That is, the body ofthe host into which analyte sensor 530 is inserted may be used as theelectrolytic medium to enable a chemical reaction that produceselectrical energy, as in a battery. For example, electrolytes within thebody can be used to transfer electrons in a chemical reaction anddevelop a detectable voltage that can be monitored and used to triggeranalyte sensor system 308 to exit the lower power state.

Using Other Signals to Exit the Lower Power State

According to embodiments, additional aspects of the present disclosureinvolve using secondary sensors or means other than analyte sensor 530(with reference to FIG. 5, by way of example) for activation purposes ina pre-connected analyte sensor system 308. Various events may bedetectable by analyte sensor system 308, where such events areindicative of implantation of analyte sensor 530. Examples includeanalyte sensor system 308 separating from an applicator, analyte sensorsystem 308 separating from packaging, and detecting the proximity ofanalyte sensor system 308 to the host or user. These events or phasechanges may be detected using a multitude of various sensor types, asdescribed below.

A first category of sensor types that may be used for detectingimplantation related events involves activation detection circuit 520using one or more signals generated by components that are included inanalyte sensor system 308 without using additional components. Thiscategory of sensor types may be advantageous because such sensors can beself-contained within analyte sensor system 308, and hence may be lowerin cost and complexity, and they typically do not require userinteraction.

One example of a technique in the first category of sensor types uses aproximity sensor for purposes of activating analyte sensor system 308.Such a sensor can detect or approximate a distance and/or change indistance between analyte sensor system 308 and a reference point, wherethe reference point may be the host, an applicator for analyte sensorsystem 308, packaging for analyte sensor system 308, or another object.Referencing FIG. 5, a proximity sensor may be implemented using one ormore of activation detection circuit 520 and activation detectioncomponent 545.

In embodiments, a proximity sensor may be implemented using capacitivesensing. For example, activation detection circuit 520 may includecapacitive coupling circuitry that can detect and/or measure conductiveobjects or other objects that have a dielectric constant different thanair. In this connection, two capacitive sensing types may be employed.

The first type of capacitive sensing may involve detecting a mutualcapacitance between capacitive coupling circuitry and another object.The other object, such as, for example, the finger of the host or user,the skin of the host or user, the baseplate of an applicator, or anyother object, may alter the mutual coupling between electrodes that maybe included in activation detection component 545. Activation detectioncomponent 545 may communicate this alteration or change in the mutualcoupling to activation detection circuit 520, to trigger an activationevent, which may cause analyte sensor system 308 to exit a lower powerstate. It should be noted that in embodiments, monitoring of thecapacitive coupling is done while analyte sensor system 308 is in thelower power state.

The second type of capacitive sensing may involve self-capacitance orabsolute capacitance. Here for example, an object such as the user'sfinger or skin, or the baseplate of an applicator (see, e.g., FIGS. 6Aand 6B described in detail below), can increase the parasiticcapacitance of the capacitance sensor to ground, thus increasing thecapacitive loading on a capacitance sensor of activation detectioncomponent 545. This capacitive loading event can be communicated toactivation detection circuit 520, to trigger an activation event.

In embodiments, the proximity sensor may be implemented using inductivesensing. Inductive sensing can be employed to implement a non-contactelectronic proximity sensor. The sensor may be used for positioning anddetection of metal and other conductive objects that may be located inone or more portions of activation detection component 545 within theapplicator for analyte sensor system 308. Here, reference is made toFIGS. 6A and 6B by way of example. The inductive sensing-based proximitysensor of activation detection component 545 may include an inductionloop. Electric current usually generates a magnetic field. When themagnetic field changes, the changing field may generate a current. Theinductance of the loop may change according to the proximity of a metalobject altering the current flowing through the loop. The change ininductance can be detected using sensing circuitry that may be includedin activation detection circuit 520 and/or activation detectioncomponent 545, the change can be used to trigger analyte sensor system308 to exit the lower power state.

Another approach for implementing a proximity sensor is to employ amagnetic detector and/or sensor. Accordingly, embodiments of activationdetection component 545 include a magnet that may be placed withinpackaging of analyte sensor system 308, within an applicator of analytesensor system 308 (see, for example, FIGS. 6A and 6B), or on or within adisplay device utilized to interact with and/or display analyte valuesfor a user. The proximity sensor can be configured to trigger anactivation of analyte sensor 308 based on the presence or absence of adetected magnetic field (for example, a Hall effect sensor, Reed switch,or the like). The presence or absence of the detected magnetic field canthen be used to trigger analyte sensor system 308 to exit the lowerpower state. More specifically, in some embodiments, a magnetic-basedsensor may use a Hall effect, Reed switch, or other magnetic means foractivation purposes. For example, a component within the applicator ofanalyte sensor system 308 (e.g., a needle hub, spring, needle, or thebody of the applicator) or on a display device configured to allow auser to interact with and/or view information related to analyte sensorsystem 308 may be magnetized or may contain a magnet. The motion causedby deployment of analyte sensor system 308, removal of the same from theapplicator, or motion of such a display device with respect to analytesensor system 308 may trigger the magnetic-based sensor.

For instance, a conductive, flexible puck may be designed to makecontact with a corresponding split connector within analyte sensorsystem 308 when analyte sensor system 308 is deployed. Once the flexiblepuck contacts the split connector, a short-circuit may be formed,causing analyte sensor system 308 to activate after detecting theshort-circuit through an impedance measurement or through a resultingconnection to power (e.g., battery). For example, a pull-up/pulldowncircuit may be triggered using the puck. In another example, processor535 can monitor for an interrupt signal from a Reed or Hall-effectswitch or the like, which interrupt signal may be generated when theswitch is no longer in sufficient proximity to a magnet that may beplaced within the applicator of analyte sensor system 308 or withinpackaging for the same.

FIGS. 6D and 6E illustrate top views of respective example embodimentsof split connectors 640, 650 of analyte sensor electronics module 12that may be included in activation detection component 545. FIG. 6Dillustrates an embodiment of an example split connector 640 having agenerally axial symmetric layout, where connector 640 is split into twosemicircular partial contacts 642 a and 642 b. FIG. 6E illustrates a topview of an embodiment of an example split connector 650 having agenerally concentric (co-axial) design, where a first partial contact652 a is encircled by a second partial contact 652 b. A space may beprovided between contacts 652 a and 652 b to insulate contacts 652 a and652 b from one another.

In some embodiments, while in a lower power mode, analyte sensor system308 may monitor for an interrupt signal from a Reed switch. Inembodiments, an interrupt signal is sent from a Reed switch when theswitch is put in a second state (e.g., open state), which may occur whena magnet is no longer in sufficient proximity to the Reed switch to keepthe Reed switch in the first state. For example, a magnet can be placednear to activation detection component 545 during manufacturing to keepanalyte sensor system 308 in the lower power mode while analyte sensorsystem 308 is in packaging or a container thereof and/or in anapplicator therefor. When it is desired to use analyte sensor system 308and implant analyte sensor 530 into the user/host, analyte sensor system308 can be removed from the container and/or packaging and the magnetmay correspondingly be moved from being in proximity of activationdetection component 545, thus causing analyte sensor system 308 totrigger activation. For example, a Reed switch, hall-effect switch, orthe like can reside in analyte sensor system 308 to cause activationdetection component 545 to trigger analyte sensor system 308 to exit thelower power state. Activation may occur, for example, when analytesensor system 308 is removed from its product packaging. The switch canalso be activated when analyte sensor system 308 is moved from being inproximity to the applicator.

In some embodiments, an interrupt signal is generated by and sent from amagnetic sensor, e.g., a Reed switch, when a magnet is brought intosufficient proximity to cause the magnetic sensor to change states. Forexample, a magnet (e.g., a thin, 10-30 mil self-adhesive magnet ormagnetic sticker) can be affixed to, e.g., any of display devices 110,120, 130, and 140 shown in FIG. 1. In some implementations, when a userwishes to wake analyte sensor system 308, for example to obtain one ormore analyte concentration values (e.g., glucose concentration values)on demand, a user can touch analyte sensor system 308 with the magnet,affixed to the display device, or bring the magnet sufficiently close toanalyte sensor system 308 for the magnetic sensor to change states. Insome embodiments, the magnetic sensor can be configured to differentiatebetween different relative motions, spatial orientations and/oralignments of the magnet and/or its magnetic field with respect to themagnetic sensor. For example, the magnet can comprise a multi-polemagnet and/or the magnetic sensor may be configured to initiate orotherwise trigger a wakeup signal in response to a specific,predetermined relative motion and/or spatial orientation of the magnetor its magnetic field and the magnetic sensor and/or display device 110,120, 130, 140. Responsive to the state change of the magnetic sensor, awakeup signal configured to cause analyte sensor system 308 to wake froma lower power consumption mode can be triggered. Upon waking from thelower power consumption mode, analyte sensor system 308 can beconfigured to initiate a wireless communication protocol (e.g., BLE)and/or power up an associated chip. Transceiver 510 can be configured tobegin advertising for example by transmitting one or more advertisingpackets. In some embodiments, the advertising packets can comprise oneor more codes and/or patterns unique to the particular wakeup protocol.The display device 110, 120, 130, 140 can receive the advertisingpackets and transmit a request for an analyte concentration value totransceiver 510. Analyte sensor system 308 can be configured to transmitone or more analyte concentration values to display device 110, 120,130, 140. Upon transmitting the one or more analyte concentrationvalues, analyte sensor system 308 can be configured to discontinuetransmitting advertising messages and revert to the lower powerconsumption mode. In response to receiving the one or more analyteconcentration values, display device 110, 120, 130, 140 can beconfigured to play a short audio clip or sound indicating to the userthat the analyte concentration value(s) has/have been received bydisplay device 110, 120, 130, 140. Such embodiments may be advantageousfor a number of reasons, including but not limited to very low cost ofimplementation, low impact on battery life, compatibility with any typeof display device, even those without certain communication protocols,and provision of a solution that minimally affects aesthetics of displaydevice 110, 120, 130, 140.

In embodiments, sonic and/or audio detection can be used to senseproximity between analyte sensor system 308 and a reference point. Forexample, activation detection circuit 520 and/or activation detectioncomponent 545 can include an ultrasonic or audio-based proximity sensorand one or more microphones and/or speakers that can use, for example, aDoppler effect to detect relative movement between an object, such asthe applicator or packing, and analyte sensor system 308. The detectedmovement can then be used to trigger analyte sensor system 308 to exitthe lower power state. By way of example, a shift in frequency of anultrasonic or audio signal may be detected using sonic/audio detectionthat analyte sensor system 308 is moving away from the applicator orpackaging in a fashion that indicates implantation is occurring or isabout to occur. In some embodiments, frequency shift may not be requiredfor detection/activation purposes. Rather, the presence or absence ofaudio/sonic signaling may be used to trigger activation of analytesensor system 308, or the presence of audio/sonic signaling of a certainamplitude or character can be used for activation purposes.

Temperature-based detection approaches may be utilized in addition to orin alternative to proximity-based techniques as another example of anelectromechanical technique in the first category of sensor types (e.g.,that do not use components external to analyte sensor system 308). Here,one or more temperature sensors can be coupled to a printed circuitboard, chip, etc. For example, activation detection component 545 mayinclude such temperature sensors that may employ a thermistor,thermocouple, or the like. The temperature sensor of activationdetection component 545 may be implemented within analyte sensor system308 and/or external thereto.

Temperature sensors can be configured to detect a temperature at asingle location (for example, a change in temperature or comparison ofthe temperature to a threshold) or multiple locations to detect atemperature gradient (for example, multiple temperature sensors can beutilized at different locations with a known distance of separation). Insome cases, temperature can be used to infer contact and/or proximitywith the user's body. For example, the temperature being closer to thetypical temperature of the human body may be indicative of proximity tothe user. The gradient measurement may be used to infer heating orcooling from a known direction, and hence, for example, may be used toinfer direction of movement of analyte sensor system 308 or anotherobject emitting heat (e.g., body of the host, etc.) or of orientationthat is closer to or further from the human body. Accordingly, adetected temperature or temperature profile can be used to triggeranalyte sensor system 308 to exit the lower power state.

In embodiments, activation detection circuit 520 and/or activationdetection component 545 may include one or more accelerometers orgyroscopes that may be used to monitor motion and orientation of analytesensor system 308 and detect one or more events indicative ofimplantation of analyte sensor 530. One such event may involve arelatively sudden increase in acceleration of analyte sensor system 308that may result, for example, from a spring activated applicatormechanism that may be used in connection with implantation of analytesensor 530 (here, reference is made for example to FIGS. 6A and 6B).Another such event may involve deceleration from analyte sensor system308 impacting a user's skin surface (e.g., hitting the user duringimplantation). In embodiments, both acceleration and deceleration eventscan be used for increasing robustness, detecting motion-related events,and/or triggering activation of analyte sensor system 308.

One potential concern in accelerometer and other deployment-basedactivation methods is power usage. For example, power usage involved inmonitoring an accelerometer signal may be proportional to the samplingfrequency used for the monitoring. Because analyte sensor 10insertion/implantation typically occurs over a relatively short timeperiod (e.g., 30 milliseconds), a relatively high sampling frequency(e.g., 5 milliseconds) may be necessary in order to reliably detectimplantation. Such a relatively high sampling frequency may correspondto higher power consumption. Accordingly, embodiments of the presentdisclosure are directed to accurately capturingacceleration/deceleration and other motion-related events using anaccelerometer while maintaining power efficiency.

In example embodiments, the sampling frequency used to monitor signalsfrom an accelerometer or other means for detecting deployment of analytesensor system 308 can be varied. For example, a lower sampling frequencycan be used for monitoring the accelerometer signal in a power efficientmanner in response to an event indicative of an upcoming deployment ofanalyte sensor system 308. Such an event may include, for example, auser un-boxing of analyte sensor system 308, the user opening packagingassociated with analyte sensor system 308, and/or the user's presence ina location/time that is typically associated withinstallation/deployment/implantation of analyte sensor system 308 (e.g.,in a hospital, clinic, user's home or other such location, as may bedetermined using location services such as GPS etc., and/or at a certaintime of day and/or date when the user prefers to or typically deploysanalyte sensor system 308).

An additional event that may be used to indicate an upcoming deploymentof analyte sensor system 308 may be or include: (1) removal of theapplicator safety mechanism, such as the applicator's safety card (e.g.,a plastic component removed from the applicator to enable triggering) orfrangible portion (e.g., a breakable portion on the trigger of theapplicator that must be removed to enable triggering); (2) push/forceapplied to the applicator (e.g., an applicator must be placed on asurface (e.g., skin surface) with a minimum force to enable triggering);(3) the breaking of a frangible member (e.g., similar to a safety ringof a plastic soda bottle); (4) the partial rotation of a threaded safetyring; (5) applying pressure to an integrated side trigger button; and/or(6) various other safety lock mechanisms. Another approach to changing asampling frequency that may be used for accelerometer monitoring mayinvolve haptic input obtained directly or indirectly from a user thatmay be detected using an accelerometer (e.g., a user may tap analytesensor system 308 to transition to a higher sampling frequency). This isdiscussed in further detail below.

Although the safety lock mechanism may be configured to beenergized/triggered by a user, in some embodiments, a pre-energizedsystem can also employ a safety lock mechanism, for example to preventpremature triggering or activation of an already energized spring.

These triggering events for the accelerometer or other activationdetection means may cause a transition in the sampling frequency used byanalyte sensor system 308 to monitor the output signal of theaccelerometer or other activation means from a relatively lower samplingfrequency to one or more relatively higher sampling frequencies, wherethe one or more higher sampling frequencies are able to more reliablydetect/capture a motion trigger or other event that occurs over arelatively short time period, such as implantation of analyte sensor530. By varying the sampling frequency, a lower amount of power may beused while still maintaining accurate event detection using anaccelerometer-based or other technique such as described herein.

While the use of positive/affirmative motion-related events is describedabove, it should be appreciated that negative motion-related events mayalso be used for triggering an activation of analyte sensor system 308and/or for changing a sampling frequency or frequencies that may be usedto monitor an accelerometer. That is, the lack of motion, orientation,or a specific location or type of location, may be used to trigger alower sampling frequency or frequencies. By way of example, if analytesensor system 308 has been relatively immobile for a prolonged period orhas been in the same position/orientation for relatively prolongedperiod, a lower sampling frequency may be employed. As an additionalexample, if analyte sensor system 308 is determined (e.g., based on GPS,A-GPS, location detection, user check-in, or using other locationservices) to be located in a storage facility, a lower samplingfrequency may be employed. This may enable power savings withoutsacrificing the accuracy of implantation detection, where the conditionsindicate that implantation is unlikely to occur.

FIG. 9 provides example plots illustrating the operation of analytesensor system 308 in connection with an accelerometer-based or otherdetection scheme that employs a variable sampling frequency in order toreduce power consumption and/or accurately detect implantation ofanalyte sensor 530, while also maintaining the ability to reliablyactivate analyte sensor system 308 and avoid false wakeups (e.g., tomore reliable calculation of analyte values, etc.). For example, theaccelerometer signal may be used in a power efficient sampling frequency(e.g., 1 s, 2 s, 5 s, 30 s, 1 min, greater than 1 min, depending uponthe application) to detect an event, such as but not limited to: motionassociated with unboxing or opening packaging, locating an installationarea, applicator safety removal, and/or applicator triggering. Oncedetected, such an event can be used to cause the accelerometer to besampled more frequently (e.g., less than 1000 ms, 500 ms, 250 ms, 100ms, 50 ms, 10 ms, etc.), where the higher frequency can enable morereliably capturing a motion trigger event. Alternatively, oradditionally, events may be detected that involve a relative lack ofmotion or an orientation, and such events may be used to trigger a lowersampling frequency in certain instances.

Plot 900 represents one or more operational states of analyte sensorsystem 308, as plotted against time (e.g., seconds). For example, theone or more operational states may include a non-triggered state and atriggered state of analyte sensor system 308. The non-triggered statemay in various cases include or be an inactive or substantially inactivestate, a lower-power state, a sleep mode, and/or the like. At point 902of plot 900, a measurement device (e.g., a potentiostat) that may beused in connection with analyte sensor system 308 detecting an analytein a host may be responsive to certain input events. For example, whenanalyte sensor system 308 is in the non-triggered state, one or moreelectrodes of analyte sensor 530 may be voltage biased and/or used tomeasure the analyte or gather information related thereto. It shouldalso be appreciated that in certain embodiments, during thenon-triggered state, the one or more electrodes of analyte sensor 530may not be biased. For example, biasing of the electrodes may in somecases be largely reduced or avoided during the non-triggered state. Thismay be based on monitored environmental or other conditions as describedherein, predetermined variables or settings, etc.

At point 904, analyte sensor system 308 is shown in the triggered state.The triggered state may in various cases be thought of as analyte sensorsystem 308 being in an active or substantially active state. In exampleimplementations of the triggered state of analyte sensor system 308,analyte sensor 530 may be voltage biased using the measurement device ormay otherwise be caused to measure/characterize the analyte.Furthermore, in the triggered state of analyte sensor system 308, othercomponents of analyte sensor system 308 may be operated, for example,connectivity interface 505 may receive/transmit data, processor 535 mayexecute various operations, etc. Region 910 of plot 900 represents anexample of a transition between the non-triggered state and thetriggered state of analyte sensor system 308.

As further illustrated in FIG. 9, plot 912 may represent an example of asignal that may be used in connection with changing an operationalstatus/state of analyte sensor system 308 vs. time (e.g., seconds). Thesignal can be monitored (e.g., over time) and used to change orotherwise control the operational status/state of analyte sensor system308, one or more components thereof, and/or circuitry within activationdetection circuit 520 of analyte sensor system 308. For example, suchcomponents and/or circuitry can be used to monitor an output signal froman accelerometer or other activation detection means that may be used inconnection with activation detection component 545.

At time region 916, for example, the signal may be at or relatively neara first value (e.g., a relatively lower value is shown in FIG. 9, thoughit should be appreciated that the first value could be a relativelyhigher value). Additionally, or alternatively, the signal could be,include, and/or be used to convey an otherwise different value, a trend,a frequency, a slope, a gradient, and/or the like, etc. that may beobserved/detected. For example, the first value etc. could becompared/measured on an absolute or self-relative basis and/or vis-à-visother values/characteristics for the signal that may occur at differenttime regions, such as those shown in plot 912. The first value etc. ofthe signal can be used to indicate that analyte sensor system 308,components thereof, and/or monitoring circuitry may be maintained in thenon-triggered state.

And, for example, at time region 914, the signal may be at or relativelynear a second value (e.g., a relatively higher value is shown in FIG. 9,though it should be appreciated that the second value could be arelatively lower value). Additionally, or alternatively, the signalcould be, include, and/or be used to convey an otherwise differentvalue, a trend, a frequency, a slope, a gradient, and/or the like, etc.that may be observed/detected. For example, the second value etc. couldbe compared/measured on an absolute or self-relative basis and/orvis-à-vis other values/characteristics for the signal that may occur atdifferent time regions, such as those sown in plot 912 in FIG. 9. Thesecond value etc. can alone or, for example, in combination with thefirst value and/or other variables/conditions, be used to indicate thatanalyte sensor system 308, one or more components thereof, and/ormonitoring circuitry may, for example, maintain analyte sensor system308, components thereof, and/or the monitoring circuitry in thenon-triggered state, but may more actively monitor an output signal fromthe accelerometer and/or other activation detection means that may beused in connection with activation detection component 545.

FIG. 9 also shows that plot 912 may include sampling period 918 that maybe employed before the occurrence of trigger 906. In response to trigger906, sampling period 920, which may be shorter than sampling period 918(e.g., thus representing a higher sampling frequency), may be employed.By way of example, trigger 906 may be an acceleration/deceleration eventassociated with un-boxing analyte sensor system 308, or any othertriggering event described herein. Using shorter sampling period 920,the monitoring circuit may be enabled to detect a motion-based and/orother event associated with upcoming, currently occurring, or pastimplantation of analyte sensor 530, which is represented here by way ofexample by trigger 908. In response to trigger 908, analyte sensorsystem 308, components thereof, the measurement device, and/ormonitoring circuitry transitioned from the non-triggered state 902through transition region 910 into the triggered state 904. Trigger 908may initiate a transition of analyte sensor system 308 from a lowerpower state to a more active state, for example.

In embodiments, a wireless/antenna-based technique may be used forpurposes of activating analyte sensor system 308. For example,activation detection component 545, portions of which may be internal toanalyte sensor system 308 and/or portions of which may be external toanalyte sensor system 308, may include a component such as an NFC orRFID tag that may be placed in proximity to analyte sensor system 308.By way of example, such a tag may be located within an applicator foranalyte sensor system 308 or within packaging for analyte sensor system308 (see FIGS. 6A and 6B, for example). Analyte sensor system 308 may,at a regular interval, interrogate the tag to establish a proximityrelationship. For example, analyte sensor system 308 may use atransmitter that may be part of the transceiver 510 to send/receive aping or other message/signal to/from the tag. If analyte sensor system308 does not receive a response to the ping or other message/signal, thelack of response may be used to indicate deployment of analyte sensorsystem 308 (e.g., insertion of analyte sensor 530) and therefor triggerexiting a lower power mode. In embodiments where analyte sensor system308 continues to send ping messages after deployment, analyte sensorsystem 308 can receive input indicating that deployment has occurred(e.g., via a GUI of a connected display device 310), and as a resultcease sending the ping messages. In some cases, the tag may be an activecomponent that pings analyte sensor system 308 or the activationdetection component. In such cases, if analyte sensor system 308 stopsreceiving pings from the tag, the lack of ping messages being receivedmay be used to indicate deployment of analyte sensor system 308.

In example embodiments, during deployment of analyte sensor system 308or removal of the same from packaging, NFC or RFID may be used to detectan alteration in the proximity relationship between analyte sensorsystem 308 and a reference point such as the packaging, and thealteration may be used to trigger analyte sensor system 308 to exit alower power state. Alterations of the proximity relationship may also bedetected using measurements that may be made, for example, bytransceiver 510, such as RSSI or other channel measurements that mayindicate proximity from a reference point. These measurements (e.g.,RSSI) may be used to trigger analyte sensor system 308 to exit the lowerpower state when the estimated distance between the reference locationand analyte sensor system 308 satisfies a condition such as specificthreshold distance for example. Additionally, in certain embodiments,NFC can be used to provide a wakeup command (e.g., from one or moredisplay devices) to analyte sensor system 308 to activate the analytesensor system 308. Alternatively, the lack of an NFC ping, or the NFCping dropping below a certain power level, can be used to indicate alack of proximity and hence trigger activation of analyte sensor system308.

In other examples, analyte sensor system 308 may utilize a radiofrequency echo to trigger analyte sensor system 308 to exit a lowerpower state. For example, analyte sensor system 308 may use transceiver510 to intermittently emit an RF signal and monitor the echo of the samefor parameters that may be known (e.g., well characterized) for a givenenvironment (e.g., within packaging or an applicator). Such parametersmay include signal strength, Doppler, distance, density, and material,by way of example. If subsequent emissions and resulting echoes change,this may indicate a change in environment that may be used to triggeractivation. Accordingly, embodiments involve detecting environmentalchanges using radio waves to determine range, angle, or velocity ofobjects surrounding analyte sensor system 308 using bounce-back oftransmitted signals to characterize (e.g., changes) in the surroundingenvironment. For example, phase angle and the like can be measured tocharacterize the surrounding environment. One example of an RF emissionmay involve BLE (Bluetooth Low Energy). In one example, one or morewireless sources may broadcast wireless signals from one or morespecific locations. The wireless source(s) may be localized to one ormore facilities or other locations where analyte sensor system(s) 308may be stored, or to a manufacturing location associated with analytesensor system(s) 308. In some examples, the wireless source(s) may beBLE sources or RF sources as described herein. In embodiments, theanalyte sensor system 308 (e.g., while located in the storage facility)may be configured to monitor or listen to the broadcasted wirelesssignals or signal characteristics and determine whether the receivedbroadcasted signal characteristic (e.g., signal strength or otheraspects) is above, below, or near a threshold. Based on thedetermination, analyte sensor system 308 may or may not transition froma lower-power/sleep mode to an active mode. For example, if the receivedsignal characteristic is above a threshold (e.g., which may indicatethat analyte sensor system 308 is still within the storage facility),analyte sensor system 308 may remain in the lower-power or sleep/shelfmode. In another example, when analyte sensor system 308 is moved toanother location (e.g., a patient's home or a doctor's office or furtheraway from the storage facility) analyte sensor system 308 may determinethat the monitored signal characteristic is below the threshold. Assuch, analyte sensor system 308 may then transition to an active oroperational mode from the lower-power mode.

Activation detection component 545, in embodiments, includes an airpressure sensor that may be used in connection with activating analytesensor system 308. For example, activation detection component 545 mayinclude an air pressure sensor that may be configured to detect changesin air pressure. The air pressure sensor may be, along with analytesensor system 308, stored in packaging pressurized above (e.g., greaterthan 1 atm) or below normal (e.g., vacuum) typical barometric pressureconditions. The act of breaching (e.g., opening, piercing, etc.) thepackaging associated with analyte sensor system 308 may then result in achange in pressure. A pressure transition event may then be used as adetectable event for triggering activation of analyte sensor system 308when the packaging is breached and the pressure changes. Analyte sensorsystem 308 may be configured to have a flexible portion (e.g.,diaphragm) that may allow pressure changes outside of a moistureprotected volume (e.g., a sensor measurement electronics housing) withinanalyte sensor system 308 to be detected within the moisture protectedvolume. Where analyte sensor system 308 is delivered in a multipackconfiguration, each analyte sensor system 308 in the multipack may haveindividual pressurized chambers within the packaging, such that eachanalyte sensor system 308 may exit the lower power state individuallybased on pressure changes.

In embodiments, activation detection component 545 includes a microphone(e.g., passive or active device) that may be located within analytesensor system 308 and used to detect an audio signal or signatureindicative of deployment of analyte sensor system 308. For example, theaudio signal/signature may be associated with the applicator deployinganalyte sensor system 308 (e.g., applicator trigger, mechanism, impactwith user). Such audio signal/signatures may be specific to deploymentevents such that they may be used to trigger analyte sensor system 308to exit a lower power state.

In some embodiments, activation or waking of analyte sensor system 308may be triggered based, at least in part, on successful deployment ofanalyte sensor system 308 as determined based, at least in part, ondetection of a sound or acoustic signature indicative of successfuldeployment by a display device configured to provide informationregarding analyte sensor system 308 to a user. Such embodiments canprovide early deployment failure detection and/or a successfuldeployment detection. For example, certain spring-based applicators canmake sounds or have an acoustic signature during deployment operationfrom which timing of moving parts can be inferred without opening orinspection of the applicator. Accordingly, an application running on anyof, e.g., display devices 110, 120, 130, 140 can be configured to, onceopen and running, differentiate unsuccessful analyte sensor system 308deployment from successful deployment and, in some cases, further inferthe specific cause of an unsuccessful deployment by analyzing a soundmade by the applicator during deployment. Such embodiments would notonly allow another, in some cases supplementary, method of verifyingsuccessful deployment for proper wakeup of analyte sensor system 308,but also allow for troubleshooting the cause of particular deploymentfailures in the field in near real-time, without a need for returning adefective applicator and/or analyte sensor system 308 to themanufacturer for investigation into the cause of failure. Suchinformation can be valuable at least in that it can allow for review ofissues mapped to particular applicator lots, it can allow furtherinnovations in future applicator and analyte sensor system design andcan reduce the costs associated with returning and investigating failedapplicators.

In some embodiments, a microphone of display device 110, 120, 130, 140can be configured to generate a recording of one or more audio waveformsand/or spectrograms of a sound made by the applicator and/or analytesensor system 308 during deployment. The application running on displaydevice 110, 120, 130, 140 can be configured to analyze the one or morerecorded waveforms and/or spectrograms and differentiate successfuldeployments from unsuccessful deployments based on the analysis. Forexample, the application can be configured to record an audio waveformand/or spectrogram at a predetermined sampling rate (e.g., 96 kHz) suchthat a desired granularity in the time course of deployment can beobtained (e.g., capability to differentiate between aspects of soundsand/or audio signatures at 1 ms±0.025 ms). In some embodiments, theapplication can be configured to isolate, correlate and/or identifyportions of the recorded waveforms and/or spectrograms indicative ofspecific parts of the applicator and/or analyte sensor system 308performing known movements as a part of the deployment process andidentify if and/or when such specific parts are performing such knownmovements within a timeframe, at a certain speed and/or at anappropriate time with respect to one or more other movements or soundsrelated to the deployment sufficient to infer a successful, oralternatively unsuccessful, deployment. Examples of such isolated soundscan include but are not limited to one or more clicks indicative of apart latching and/or releasing from another part, and/or one or morebangs or sound peaks indicative of a drive wheel or booster moving,rotating and/or stopping. In some embodiments, upon determination of anunsuccessful deployment, the application can provide one or morenotifications to the user, e.g., “Remove sensor,” indicating anunsuccessful deployment, or alternatively one or more notifications tothe user indicating a successful deployment. In some embodiments, upondetermination of a successful deployment, the application can provideone or more notifications to the user indicating the successfuldeployment.

Activation detection component 545 may include an optical-based sensorthat can

be used to cause analyte sensor system 308 to exit the lower powerstate. By way of illustration, such an optical-based sensor may bephotovoltaic. A voltage may be generated based on exposure of theoptical sensor to photons. The generated voltage may then be compared toa threshold in the result of the comparison may be used to triggeractivation of analyte sensor system 308. The optical-base sensor maythus use exposure to light for activation purposes. The sensor may beexternal to analyte sensor system 308, or, for example, may be locatedwithin analyte sensor system 308 and covered by an optically transparentportion of the housing of analyte sensor system 308 such that light maystill reach the optical-based sensor. In embodiments, the optical-basedsensor may include a CMOS device, CCD device, a photodiode,photoresistor, and/or phototransistors that may be triggered by exposureto normal daylight conditions or when the light exposure satisfies athreshold condition. Such optical-based sensors may be considered to bepart of activation detection component 545 that is separate fromactivation detection circuit 520 or may be encompassed within activationdetection circuit 520. In one example, the user equipment (UE) devices(e.g., display device 310) may provide the light signal that may be usedto activate analyte sensor system 308 (e.g., an LED light source fromthe UE device may be used). In another example, exposure to light mayoccur when a sticker or other element that covers the detector isautomatically removed when analyte sensor system 308 is removed from theapplicator or packing thereof.

Activation detection circuit 520 and/or activation detection component545 may include a conductivity-based sensor that may be used to triggeranalyte sensor system 308 to exit a lower power state. Such a sensor mayutilize resistance measured through a user's skin when analyte sensorsystem 308 has been deployed. For example, a conductivity-based sensormay measure a large (e.g., open circuit) resistance before analytesensor system 308 has been deployed and analyte sensor 10 has beenimplanted in the user. However, once analyte sensor system 308 isdeployed and analyte sensor 10 implanted, the resistance measured by theconductivity-based sensor may decrease via a conductive path through theuser's skin. The conductive path may be measured between two electrodesof activation detection circuit 520 and/or activation detectioncomponent 545. For example, a first conductive probe may contact thesurface of the user's skin during deployment, and resistance may bemeasured from the first conductive probe to an electrode of analytesensor 10, where the measured resistance is detectably lower duringdeployment than before deployment. Alternatively, or in addition, two ormore conductive probes may contact the surface of the user's skin indifferent locations separated by a distance (e.g., several millimeters)and, relative to the resistance measured between the probes beforedeployment, a lower resistance may be measured between these (e.g., two)conductive probes after deployment of analyte sensor system 308. Thechange in the measured resistance before and after deployment may beused to trigger analyte sensor system 308 to exit the lower power state.

In some cases, one or more electromechanical or mechanical-basedswitches or sensors may be used for activation purposes. In embodiments,activation detection component 545 includes a switch-based sensor. Forexample, a mechanical switch may be located on analyte sensor system308. The switch can be sealed (e.g., using a gasket) such that theexternal and internal portions of analyte sensor system 308 may beisolated from one another. The switch-based sensor may use a momentaryor latching switch and may be used to connect circuits of analyte sensorsystem 308 to a power source (e.g., a battery of analyte sensor system308) in order to trigger circuit wakeup (e.g., by forming a connectionthrough a wakeup pin). The switch may be triggered by analyte sensorsystem 308 being unboxed/unpackaged, by the applicator duringdeployment, and/or by analyte sensor system 308 hitting/impacting theuser during deployment. The switch may be mechanically triggered and mayrelease when analyte sensor system 308 is deployed.

In embodiments, activation detection circuit 520 and/or activationdetection component 545 may include two or more exposed contactsconfigured in an open circuit that may be used to cause analyte sensorsystem 308 to exit a lower power state. By way of example, electricalcontacts external to analyte sensor system 308 may be part of an opencircuit that is internal to analyte sensor system 308. Bridging (e.g.,using an electrical jumper) two such electrical contacts, such that theelectrical contacts form an electrical connection with one another(e.g., using another conductive material to form the bridge), maytrigger activation of analyte sensor system 308. Alternatively, two suchelectrical contacts may already be electrically connected to oneanother, and the act of breaking this connection may trigger activationof analyte sensor system 308. For example, bridging orun-bridging/disconnecting the electrical contacts may pull a node up ordown to trigger activation of analyte sensor system 308, and/or form aconnection to a battery of analyte sensor system 308 as a means oftriggering activation. Aspects of this are described further withreference to FIG. 6C.

The above-described bridge may be located in or may be part of theapplicator of analyte sensor system 308, such that the bridge may beused to trigger activation when analyte sensor system 308 exits theapplicator (e.g., the bridge may be broken or formed). The bridge may belocated in a baseplate of analyte sensor system 308 and may be used totrigger activation during assembly of analyte sensor system 308 (e.g.,the bridge may be broken or formed). For example, during assembly ofpre-connected analyte sensor system 308, two mechanicallyseparate/connectable pieces may be joined by the user or the applicator,and this joining may form or disrupt the bridge, triggering activation.

The bridge described above may be used to connect power (e.g., from abattery of analyte sensor system 308) or to trigger circuit wakeup(e.g., using a wakeup pin). The bridge can be used to facilitateautomatic wakeup of pre-connected analyte sensor system 308 via needleretraction, where the needle serves as a bridge (e.g., jumper) betweentwo sets of contacts on a circuit board using a multilayer gasket withan insulating layer in the middle separating two conductive layers.While the needle is bridging the gasket, the circuit may bebridged/closed. And once the needle is retracted (e.g., duringdeployment of analyte sensor system 308), the circuit may bebroken/opened/unbridged, triggering activation. One benefit of using agasket through the needle pathway is the reduction in the size of theopening through the assembly of analyte sensor system 308, which couldhelp with potential concerns regarding ingress of debris and bloodvisibility to the user. This can help prevent debris and excess moisturefrom reaching the wound site and hide blood from the user.

FIG. 6A illustrates applicator 7100 for an on-skin sensor assembly ofanalyte sensor system 308, according to embodiments of the disclosure.Applicator 7100 may include activation element 7104 disposed on a sideof applicator 7100, for example, on a side of outer housing 7101 ofapplicator 7100. In some embodiments, activation element 7104 may be abutton, a switch, a toggle, a slide, a trigger, a knob, a rotatingmember, a portion of applicator 7100 that deforms and/or flexes, or anyother suitable mechanism for activating an insertion of analyte sensor530 and/or retraction assembly of applicator 7100. In some embodiments,activation element 7104 may be disposed in any location, e.g., a top,upper side, lower side, or any other location of applicator 7100.Applicator 7100 may be large enough for a host to grasp with a hand andpush, or otherwise activate, activation element 7104 with, for example,a thumb, or with an index finger and/or a middle finger. Applicator 7100may be sized appropriately to house analyte sensor system 308, as wellas one or more components of activation detection component 545described above.

Applicator 7100 may be configured with one or more safety features suchthat applicator 7100 can be prevented from activating until the safetyfeature is deactivated. In one example, the one or more safety featuresmay prevent applicator 7100 from activating unless applicator 7100 ispressed against the skin of a host with sufficient force. Moreover,applicator 7100 may be further configured such that one or morecomponents therein retract based at least in part on the one or morecomponents pushing against the skin of the host with a force exceeding apredetermined threshold, rather than based on the one or more componentstranslating beyond a predetermined and static distal position. In otherwords, applicator 7100 may implement force-based retraction triggeringrather than being limited to displacement-based retraction triggering.

FIG. 6B illustrates an exploded perspective view of applicator 7100 ofFIG. 6A, according to some embodiments. As shown, applicator 7100 mayinclude outer applicator housing 7101 that may include activationelement 7104. Outer applicator housing 7101 may be configured totranslate in a distal direction by a force applied by a host toapplicator 7100, specifically to inner housing 7102, thereby aligningactivation element 7104 in a position that allows applicator 7100 tofire.

Applicator 7100 can further include inner housing 7102, configured tohouse at least one or more mechanisms utilized to apply analyte sensorassembly 360 (for example, as referenced above in connection with FIG.3A) to the skin of a host. As mentioned above, analyte sensor assembly360 may include or house analyte sensor system 308. A distal surface7130 of a bottom opening of inner housing 7102 may define a bottomsurface of applicator 7100. In some embodiments, upon applicator 7100being pressed against the skin of a host, the skin may deform in asubstantially convex shape at distal surface 7130 such that at least aportion of a surface of the skin is disposed at the bottom opening ofapplicator housing 7102 extends into the bottom opening of inner housing7102 beyond a plane defined by distal surface 7130 in a proximaldirection. One or more components of activation detection component 545described above may be included in or on inner housing 7102, such as,for example, NFC components, magnets, etc., or any other of thecomponents describe above that may be external to analyte sensor system308. In some embodiments, barrier layer 7194 may be disposed over thebottom opening of inner housing 7102.

Activation of applicator 7100 may include a host pressing applicator7100 against the skin with sufficient force to translate outer housing7101 in a distal direction toward and with respect to inner housing 7102until activation element 7104 is aligned with aperture 7106 of innerhousing 7102. Once such an alignment is achieved, a host may initiate(e.g., pushing) activation element 7104. In some other embodiments,applicator 7100 may be configured such that activation element 7104 maybe activated first, but that actual insertion is not triggered untilouter housing 7101 is translated sufficiently in the distal directiontoward and with respect to inner housing 7102. In yet other embodiments,activation element 7104 may be biased toward a center of applicator 7100such that activation element 7104 need not be explicitly activated bythe host but, instead, activation element 7104 may be configured toautomatically initiate insertion upon outer housing 7101 beingtranslated sufficiently in the distal direction toward and with respectto inner housing 7102.

By way of example, FIG. 6C illustrates a bridge-based sensor or switchthat may be used in connection with activation of analyte sensor system308. FIG. 6C shows portions of analyte sensor electronics module 600that is connectable to analyte sensor 602 using first and secondcontacts 604 and 606. For example, analyte sensor electronics module 600may be connected to analyte sensor 602 before analyte sensor 602 isimplanted in the user. Analyte sensor electronics module 600 may includeconductive bridge 612 (e.g., a jumper), which may be configured toelectrically couple first and second contacts 604 and 606 to one anotherto form a bridge during deployment/application of analyte sensor system308. Conductive jumper 612 can be located at least partially between twoelectrical connections of analyte sensor system 308. Conductive jumper612 can include two springs 608 coupled by conductive link 616, whereconductive jumper 612 and springs 608 are supported by housing 614 ofanalyte sensor system 308. During deployment/application of analytesensor system 308, springs 608 may be deflected such that springs 608electrically connect to one another through physical contact, thusforming a bridge that may be used to trigger activation of analytesensor system 308.

Referring back to FIG. 5, and with reference being made to FIG. 6C byway of example, activation detection circuit 520 and/or activationdetection component 545 may include a non-conductive separationtab-based sensor or switch that may be used to cause analyte sensorsystem 308 to exit a lower power state in various embodiments. Forexample, a non-conductive material may be placed between spring-loadedelectrical contacts. The removal of the nonconductive material may thencause the spring-loaded electrical contacts to form aphysical/electrical connection, electrically coupling the contacts. Theconnection of these spring-loaded electrical contacts may be used toconnect power (e.g., from a battery of analyte sensor system 308) and/orto trigger circuit wakeup (e.g., as a wakeup pin) and cause analytesensor system 308 to exit a lower power state.

In embodiments, activation detection circuit 520 and/or activationdetection component 545 may include a strain/force-based sensor that maybe used to cause analyte sensor system 308 to exit a lower power mode.One or more sensors may be included in analyte sensor system 308 thatmay be capable of detecting a strain (e.g., total deformation divided byinitial dimension of the body) or a force placed on a housing/body ofanalyte sensor system 308. Such strain or force may be applied, forexample, by an applicator gripping analyte sensor system 308. In someexamples, a strain gauge may be used on the interior of the housing ofanalyte sensor system 308, where the strain gauge may be electricallycoupled to activation detection circuit 520, for example, throughrouting on a printed circuit board, etc. The strain gauge may be placedon our coupled to a Wheatstone bridge. The strain gauge may vary aresistance value which can be monitored using the Wheatstone bridge.Various types of strain gauge configurations may be used in connectionwith the Wheatstone bridge, for example, quarter-, half-, andfull-bridges may be used depending upon the orientation of the straingauges and type of strain being measured. The strain/force measurementmay also be used to detect a momentary action such as the forces ofacceleration during deployment of analyte sensor system 308 and/or theimpact of analyte sensor system 308 on the user's body. For example, thestrain/force measurement may be used to effect triggers 906 and/or 910,with reference to FIG. 9.

In certain embodiments, activation detection circuit 520 and/oractivation detection component 545 may include additional componentsthat may be added internally to or externally from analyte sensor system308 specifically for creating detectable events that may be used totrigger activation of analyte sensor system 308 without userintervention. In one example, a current generating component may be usedin conjunction with analyte sensor system 308 for activation purposes.For instance, magnetizing or adding a magnetic element to the applicatorneedle or needle hub may be used for activation purposes. As analytesensor system 308 is deployed, the magnetic needle or auxiliary magneticrod can be retracted in relation to analyte sensor system 308.Activation detection component 545 may include induction coils or an NFCantenna, for example on the perimeter of analyte sensor system 308, thatmay be used to generate current (e.g., or other electrical signal) viaelectromagnetic response. The motion of the applicator withdrawing theneedle, rod, or other magnetic element can create relative motionbetween the same and the coil/antenna of analyte sensor system 308. Thiscurrent or other electrical signal can then be used to triggeractivation of analyte sensor system 308. In some cases, analyte sensorsystem 308 may already include an NFC antenna, and thus this feature maynot require the addition of components to analyte sensor system 308.

In another example, a piezoelectric component can be used, where thepiezoelectric component generates a voltage in response to a force(e.g., impact force) that may occur during deployment of analyte sensorsystem 308. For example, a quartz crystal may be included in activationdetection circuit 520 and/or activation detection component 545, where avoltage generated by the crystal spikes or increases when analyte sensorsystem 308 experiences impact from the deployment, thus triggeringanalyte sensor system 308 to exit the lower power state.

Exiting the Lower Power State in Response to User-Based Input

In certain embodiments, switches/sensor/mechanisms/techniques can beemployed to detect a user step and trigger activation of analyte sensorsystem 308 using the same, either alone or in combination with otheractivation detection techniques/means described herein. Suchswitches/sensors/mechanisms/techniques may typically rely upon userintervention/action. In some examples, a detection switch/element/sensorcan be placed on analyte sensor system 308 and used to triggeractivation or exit from a lower power state. By way of example, at leastpart of activation detection component 545 may include a detectionelement/component that is external to analyte sensor system 308, such asa removable sticker on a surface of analyte sensor system 308. Inresponse to the user peeling/removing the sticker, analyte sensor system308 may be triggered to exit the lower power state. As another example,the detection element may be a feature of the applicator, packaging,box, or a tray associated with the delivery of analyte sensor system308. Here, reference is made to FIGS. 6A and 6B, for example. In somecases, the detection element may be a component placed in the packagingnear analyte sensor system 308.

The detection element may contain a conductive material (e.g., metal,graphite, etc.), and, in embodiments, a sensor (e.g., that usescapacitive, inductive magnetic, RF, or other type of sensing, forexample as described herein) may detect the removal of the conductivematerial when the detection element is removed by the user. In certainembodiments, the detection element may include a tag device (e.g., RFIDsticker or the like) that may be placed on a surface of analyte sensorsystem 308 during manufacturing/assembly of the same. A reader (e.g.,NFC, RFID, etc.) may then detect the removal of the tag and triggeractivation. For example, ping messages may be exchanged when the tagdevice is in place but the exchange may stop occurring once the tagdevice is removed, thus triggering activation.

In some cases, the detection element may be optically opaque such thatremoving the detection element may expose a photosensor to light, thustriggering activation. For example, a photosensor may be exposed to thelight by a sticker being pulled off to uncover the photosensor.Alternatively, the detection element may be optically tinted (e.g.,green or another color). As such removal of the detection element mayresult in a shift in wavelength that can be detected using aphotosensor. By way of example the shift in color may go from green towhite or the like, and the change in color may be used to triggeractivation.

Certain of the above-described electromechanical detection techniquesmay be employed in connection with embodiments that utilize a user stepfor purposes or activating analyte sensor system 308. For example, theuser may push a button, pull a tab, take a step that forms or breaks abridge, etc. to trigger activation of analyte sensor system 308. Theuser can be instructed to take such a step before or after analytesensor 10 implantation, or within a certain time window thereof.

In embodiments, a signal from an external device or a signal generatedbased on user input may be used to trigger activation of analyte sensorsystem 308. By way of example, the display of an electronic device(e.g., smartphone, proprietary analyte display device, or smartwatch,referencing FIG. 1) can be used to direct light (e.g., from a flash orscreen of the device, as mentioned above), audio (e.g., frequency), orvibration to analyte sensor system 308. Activation detection circuit 520and/or activation detection component 545 can then be used to detectsuch external stimuli via, for example, a photodiode, microphone, orpiezoelectric sensor, and in response thereto to trigger activation. Inone example, a user may tap a pattern on analyte sensor 308 that can bedetected using a microphone and/or an accelerometer and used to triggeractivation. An accelerometer of analyte sensor system 308 may also usepattern detection, for example, of the human gait/walk, for activationpurposes. That is, if analyte sensor system 308 detects that it ismoving in accordance with the human gait, it can be inferred thatimplantation of analyte sensor 530 has occurred.

It should be appreciated that each of the above-described techniques canbe used alone or in combination with any of the other above-describedtechniques for purposes of causing analyte sensor system 308 to exit alower power state. The technique(s) employed may depend upon systemdesign considerations, for example, including considerations regardingpower consumption, weight, size, and level of user interactivity, amongother considerations.

Utilizing a State-Machine for Exiting the Lower Power State

One or more embodiments as disclosed herein may utilize impedancemeasurements and/or current counts indicative of a current flowingthrough an analyte sensor (e.g., analyte sensor 530 of FIG. 5) todetermine when the analyte sensor has been deployed into a skin of ahost and, therefore, when at least a portion of sensor electronics(e.g., analyte sensor system 308 of FIG. 5 by way of example and notlimitation) should exit a lower power “storage” or “sleep” mode and“wake up” to begin processing one or more samples of a sensor signaland/or sensor data. Additionally, or alternatively, such current countsand/or impedance measurements may be utilized once such analyte sensorsystem 308 sensor electronics has entered a powered “run” mode toperiodically or randomly calibrate or recalibrate analyte sensor 530and/or to monitor a sensitivity of analyte sensor 530.

Some embodiments can utilize a clocked processor-based controller (e.g.,processor/microcontroller 535 of FIG. 5) to provide one or more pulsedvoltages across the terminals of analyte sensor 530, perform consecutivecurrent count and/or impedance measurements or determinations of analytesensor 530 based on a response to the pulsed voltages, average andanalyze the current count and/or impedance measurements. Such pulsedvoltages may have durations on the order of milliseconds and accurateestimation of an average current flowing through analyte sensor 530and/or an impedance of analyte sensor 530 can require many current countsamples (e.g., 125) to be averaged over an extended period of time(e.g., 10-12 seconds). While such controller-based solutions have beenshown to work, constantly powering clocked processor-based controller535 during the sample acquisition process requires a significant amountof power and can cause on-board batteries to last for only a fraction oftheir rated capacities.

One solution, as will be described in more detail below in connectionwith at least FIGS. 12-15, is to offload such a controller-based methodfor measuring and/or determining current counts indicative of a currentflowing through analyte sensor 530 to a hardware-based state machine(e.g., state machine 1430 of FIG. 14), which consumes considerably lesspower than clocked processor-based controller 535. In such solutions,clocked processor-based controller 535 can set up one or more parametersof state machine 1430 and then enter a lower power “sleep” state, ratherthan performing all actions by itself, staying “awake,” and undesirablydraining the battery. In some embodiments, state machine 1430 can beimplemented utilizing one or more registers (e.g., parameter register1436 of FIG. 14), one or more counters (e.g., counter 1434 of FIG. 14)and/or one or more memories (e.g., a portion of storage 515 of FIG. 5).

While controller 535 is in the lower power “sleep” state, state machine1430 can be tasked with controlling the application of one or morepulsed voltages across the terminals of analyte sensor 530, controllingthe measurement of a current induced in analyte sensor 530 by the one ormore pulsed voltages, and storing one or more data samples (e.g.,digital counts) based on the current response. Controller 535 may thenwake up, responsive to an interrupt or wake signal from state machine1430, to process the one or more stored data samples, the number ofwhich may be variable based on the particular implementation. Such asolution can reduce the overall power consumption of analyte sensorsystem 308, in some cases by 50-60% or more, compared to theabove-described data acquisition process utilizing only clockedprocessor-based controller 535.

State machine 1430 can be utilized to capture, at least partly process,and/or store current counts corresponding to a current flowing throughthe analyte sensor during a “storage” mode, when the controller islargely “sleeping,” or during a “run” mode when continuous analyte(e.g., glucose) measurements are being measured, determined, estimatedand/or otherwise processed.

During such a “storage” mode, an analog front end (AFE) of the analytesensor system (e.g., at least a portion of sensor measurement circuitry525 of FIG. 5) can wake periodically (e.g., every 64 seconds) andperform one or more current count measurements indicative of a currentflowing through analyte sensor 530 to determine whether analyte sensor530 has been inserted into the skin of the host, indicating that atransition from “storage” mode to a “run” mode or “wake” state isappropriate. This process can also be utilized to differentiate currentcount values indicative of analyte sensor 530 being properly insertedinto the skin from current count values indicative of analyte sensor 530being subjected to environmental conditions (e.g., high relativehumidity) that may falsely indicate sensor insertion into the skin ofthe host. Accordingly, this process can help to avoid false wakeup ofcontroller 535 due to, e.g., high relative humidity conditions, asdetailed below. For example, when analyte sensor 530 is inserted intothe skin of the host, a relatively moderate to lower impedance (e.g.,several hundred kΩ) of analyte sensor 530 will result in a certainobserved current flow through analyte sensor 530. However, when arelative humidity is sufficiently high (e.g., >90%) but analyte sensor530 is not inserted into the skin of the host, a relatively high, butnot open-circuit, impedance (e.g., 1.6MΩ) of analyte sensor 530 willresult in a different observed current flow through analyte sensor 530,where the higher the relative humidity, the greater the observed currentflow through analyte sensor 530 will be (see, e.g., FIG. 7C).State-machine 1430 described herein can allow differentiation betweenthese two states such that these environmental conditions (e.g.,sufficiently high relative humidity) do not inadvertently trigger afalse wakeup of controller 535, thereby further reducing powerconsumption due to unnecessary and inappropriate waking of controller535.

FIG. 12 illustrates a state diagram 1200 related to, e.g., state machine1430 of FIG. 14, at least for determining one or more current countsindicative of a current flowing through analyte sensor 530, inaccordance with some embodiments. State diagram 1200 illustrates 7potential states: 5 potential delay states (e.g., delay 1 WE_L state1206, delay 2 WE_L state 1212, delay 1 WE_H state 1216, delay 2 WE_Hstate 1224, and idle state 1228) and two potential sampling states(e.g., pre-count sampling state 1208 and pulse count sampling state1220). While operation of state machine 1430 is described in more detailbelow in connection with FIGS. 13-15, a brief overview here can behelpful in understanding the function and utility of the differentstates.

In order to ultimately determine an impedance of analyte sensor 530, aknown voltage may be applied across the terminals of analyte sensor 530and Ohm's Law can be used to determine the impedance based on thecurrent generated by that known voltage. However, the current generatedby the known voltage can have components that are not necessarilydirectly attributable to, e.g., a membrane impedance of analyte sensor530, but to other environmental factors. Accordingly, an impedancedetermined based on a single current or current count measured inresponse to application of the known voltage across the sensor terminalsmay not accurately reflect the actual membrane impedance of analytesensor 530 and, therefore, may not be a reliable indicator for changinga state of analyte sensor system 308, e.g., from a “sleep” or “storage”state to a “wake” or “run” state. Accordingly, it can be desirable toutilize a plurality of current or current count measurements for makingsuch a state change determination.

Accordingly, a first current count value may be determined while aworking electrode of analyte sensor 530 is held at a first potential.This first current count may be considered a baseline value. The workingelectrode of analyte sensor 530 can then be held at a second potentialgreater than the first potential and a second current count value may bedetermined. This second current count value may be considered a pulsevalue. If the interval between measurement of the first and secondcurrent count values is sufficiently small, subtracting the firstcurrent count value from the second current count value can reliablyremove much of the effect of environmental factors from the measurementsand an accurate membrane impedance value for analyte sensor 530 can beobtained therefrom based on an understanding that such impedance wouldbe inversely related to the difference between the first and secondcurrent counts, since with such sufficiently small intervals betweenmeasurements, the effects of such environmental factors can be assumedto have a similar effect on both the first and the second currentcounts.

However, when the first and second potentials are applied across theterminals of analyte sensor 530, the initial instantaneous currentsinduced through analyte sensor 530 will not be indicative of thesensor's steady-state impedance, as determined according to Ohm's Law,due to the RC characteristics of analyte sensor 530, for example aspreviously described in connection with FIG. 7A. Accordingly,implementing one or more delay states 1206, 1212, 1216, 1224 can ensurethat current counts measured during sampling states 1208, 1220 are notsubstantially affected by the initial dynamics of the RC characteristicsof analyte sensor 530.

As illustrated in FIG. 12, the order of states 1206, 1208, 1212, 1216,1220, 1224 and 1228 are always the same, but all states except pre-countsampling state 1208 can be bypassed according to a pre-configuration ofstate machine 1430 (see FIG. 14) and/or an associated parameter register1436 (see FIG. 14) by controller 535. Each state in FIG. 12 can alsohave a pre-configured duration. A counter (e.g., counter 1434 of FIG.14) can count continuously during each enabled state until aconfigurable absolute value is reached, triggering a change to the nextenabled state and a reset of counter 1434 for timing the next enabledstate. In some embodiments, this process allows a single counter 1430 totime all enabled states of state machine 1430, thereby simplifyinganalyte sensor system design and reducing associated fabrication costs.

State diagram 1200 starts at start block 1202 and advances to block1204, which determines whether a first delay state 1206 (e.g., delay 1WE_L) is enabled. If first delay state 1206 is disabled, state diagram1200 advances from block 1204 directly to a first sampling state 1208.If first delay state 1206 is enabled, state diagram 1200 advances tofirst delay state 1206, which can last for a configurable duration,e.g., ˜1-2 milliseconds or any other suitable duration. At initiation offirst delay state 1206, state machine 1430 can apply or controlapplication of a first voltage potential to a working electrode ofanalyte sensor 530. No current count measurements are captured by statemachine 1430 and/or by supporting hardware or software as shown in atleast FIG. 14 during first delay state 1206.

Upon expiration of first delay state 1206, state diagram 1200 advancesto first sampling state 1208, during which the first voltage ismaintained at the working electrode of analyte sensor 530 and one ormore samples (e.g., digital counts) corresponding to the current inducedin analyte sensor 530 by the first voltage potential are captured and/orprocessed by state machine 1430 and/or supporting hardware or softwareas shown in at least FIG. 14. First sampling state 1208 can last for aconfigurable duration, e.g., ˜2 s to 300 seconds, depending on theapplication.

Upon expiration of first sampling state 1208, state diagram 1200advances to block 1210, which determines whether a second delay state1212 (e.g., delay 2 WE_L) is enabled. If second delay state 1212 isdisabled, state diagram 1200 advances from block 1210 directly to block1214. If second delay state 1212 is enabled, state diagram 1200 advancesto second delay state 1212, which can last for a configurable duration,e.g., ˜1-2 milliseconds or any other suitable duration. State machine1430 can maintain or control the maintenance of the first voltagepotential at the working electrode of analyte sensor 530 for theduration of second delay state 1212. No current count measurements arecaptured by state machine 1430 and/or by supporting hardware or softwareas shown in at least FIG. 14 during second delay state 1212.

Upon expiration of second delay state 1212, state diagram 1200 advancesto block 1214, which determines whether a third delay state 1216 (e.g.,delay 1 WE_H) is enabled. If third delay state 1216 is disabled, statediagram 1200 advances from block 1214 directly to block 1218. If thirddelay state 1216 is enabled, state diagram 1200 advances to third delaystate 1216, which can last for a configurable duration, e.g., ˜1-2milliseconds or any other suitable duration. At initiation of thirddelay state 1216, state machine 1430 can apply or control application ofa second voltage potential greater than the first voltage potential tothe working electrode of analyte sensor 530. Initial current flowthrough analyte sensor 530 due to the RC characteristics of analytesensor 530 can occur and substantially dampen out during third delaystate 1216. Accordingly, no current count measurements are captured bystate machine 1430 and/or by supporting hardware or software as shown inat least FIG. 14 during third delay state 1216.

Upon expiration of third delay state 1216, state diagram 1200 advancesto block 1218, which determines whether a second sampling state 1220 isenabled. If second sampling state 1220 is disabled, state diagram 1200advances from block 1218 directly to block 1222. If second samplingstate 1220 is enabled, state diagram 1200 advances to second samplingstate 1220, during which the second voltage is maintained at the workingelectrode of analyte sensor 530 and one or more samples (e.g., digitalcounts) corresponding to the current induced in analyte sensor 530 bythe second voltage potential are captured and/or processed by statemachine 1430, as will be describe in more detail below in connectionwith FIGS. 13-15. Second sampling state 1220 can last for a configurableduration, e.g., ˜3-4 milliseconds, depending on the application.

Upon expiration of second sampling state 1220, state diagram 1200advances to block 1222, which determines whether a fourth delay state1224 (e.g., delay 2 WE_H) is enabled. If fourth delay state 1224 isdisabled, state diagram 1200 advances from block 1222 directly to block1226. If fourth delay state 1224 is enabled, state diagram 1200 advancesto fourth delay state 1224, which can last for a configurable duration,e.g., ˜1-2 milliseconds or any other suitable duration. State machine1430 can maintain or control the maintenance of the second voltagepotential at the working electrode of analyte sensor 530 for theduration of fourth delay state 1224. No current count measurements arecaptured by state machine 1430 and/or by supporting hardware or softwareas shown in at least FIG. 14 during fourth delay state 1224.

Upon expiration of fourth delay state 1224, state diagram 1200 advancesto block 1226, which determines whether a fifth delay state 1228 (e.g.,an extended idle state) is enabled. If fifth delay state 1226 isdisabled, state diagram 1200 advances from block 1226 directly back toblock 1204 and state machine 1430 runs through state diagram 1200 again.If fifth delay state 1228 is enabled, state diagram 1200 advances tofifth delay state 1228, which can last for a configurable duration,e.g., ˜1 millisecond to 64 seconds or any other suitable duration. Atinitiation of fifth delay state 1228, state machine 1430 can reapply orcontrol the reapplication of the first voltage potential to the workingelectrode of analyte sensor 530, can provide or control provision of 0Vto the working electrode of analyte sensor 530, or can provide orcontrol provision of an open-circuit voltage (e.g., high-Z state) to theworking electrode of analyte sensor 530 (e.g., by opening a switch inthe circuit including analyte sensor 530). This potential can bemaintained at the working electrode for the duration of fifth delaystate 1228. No current count measurements are captured by state machine1430 and/or by supporting hardware or software as shown in at least FIG.14 during fifth delay state 1228.

In some embodiments, enablement of fifth delay state 1228 can bereserved for operation of state machine 1430 during storage mode, whenanalyte sensor 530 is not actively measuring analyte values and duringwhich samples may only be collected intermittently during first and/orsecond sampling states 1208, 1220, which occur between longer periods ofinactivity defined primarily by the duration of fifth delay state 1228.

Moreover, the first and second voltages described above can be fullyconfigurable and, in some cases, independently configurable from oneanother. For example, the first and second voltages may be programmablefrom 0V to 1V in ˜16 mV steps (e.g., 64 steps). In addition, the firstand second voltages may each have different values depending on whetheranalyte sensor system 308 is currently in a “storage” mode, during whichanalyte sensor 530 is not inserted into the skin of the host, or in a“run” mode, during which analyte sensor 530 is inserted into the skin ofthe host and continuous and/or intermittent glucose measurements arebeing taken, determined and/or otherwise captured. For example, in sucha “run” mode, the first voltage can be 0.6V and the second voltage canbe 0.616V (e.g., 16 mV greater than the first voltage), while in such a“storage” mode, the first voltage can be 0V and the second voltage canbe 0.016V (e.g., 16 mV greater than the first voltage).

In some embodiments, utilization of 0V for the first voltage during“storage” mode may be advantageous since applying defined, non-zero biasvoltages across the terminals of analyte sensor 530 for extended periodsof time can cause accelerated oxidation and/or damage to sensor 530. Forsimilar reasons, applying an open-circuit voltage (e.g., a high-Zstate), or alternatively 0V, to the working electrode of analyte sensor530 during fifth delay state 1228 can help to ensure that no potentiallydamaging bias voltage is applied across the terminals of analyte sensor530 for the often extended durations of fifth delay state 1228, therebyreducing oxidation or other damage to analyte sensor 530 during“storage” mode before analyte sensor 530 is deployed into the skin ofthe host.

Moreover, while examples of the durations of each of the states in statediagram 1200 are given above, the present disclosure is not so limitedand any suitable durations are contemplated. In some embodiments,counter 1434 of FIG. 14 may comprise a configurable-bit counter. Forexample, counter 1434 may be configured as a 10-bit counter having amaximum value of 1 second and being configurable in ˜0.976 microsecond(e.g., 1/1,024th of a second) increments when timing each of first delaystate 1206, second delay state 1212, third delay state 1216, secondsampling state 1220, and fourth delay state 1224. In some embodiments,counter 1434 may be configured as a 19-bit counter having a maximumvalue of 8.53 minutes and being configurable in ˜0.976 microsecond(e.g., 1/1,024th of a second) increments when timing each of firstsample state 1208 and fifth delay state 1228.

Operation of analyte sensor system 308 will be further discussed inconnection with timing diagram 1300 of FIG. 13 and functional blockdiagram 1400 of FIG. 14 together below, in accordance with someembodiments.

Timing diagram 1300 of FIG. 13 illustrates example timing of severalsignals in relation to one or more of the states previously described inconnection with state diagram 1200 of FIG. 12.

A Pulse_Count_Ready signal 1310 can be utilized to signal that a currentcount, corresponding to a current flowing through analyte sensor 530,determined and integrated by an analog-to-digital converter (ADC) of ananalog front end (AFE) (e.g., sensor measurement circuitry 525) duringsecond sampling state 1220, is ready for transmission to one or moremodules of FIG. 14.

A Pre_Count_Ready signal 1320 can be utilized to signal that a currentcount, corresponding to a current flowing through analyte sensor 530,determined and integrated by the ADC of the AFE during first samplingstate 1208, is ready for transmission to one or more modules of FIG. 14.

An INT_Enable signal 1330 can be utilized to signal the ADC of the AFEto integrate the current counts corresponding to the current flowingthrough analyte sensor 530 during one or both of the first and secondsampling states 1208, 1220, based on signal 1330 being high at 1332 and1334. Timing diagram 1300 also illustrates an example working electrodepotential 1340 for analyte sensor 530 as applied during one or more ofstates 1206, 1208, 1212, 1216, 1220, 1224, 1228.

Block diagram 1400 of FIG. 14 illustrates example features of statemachine 1430 and at least some hardware- and/or software-based featuresof, e.g., sensor measurement circuitry 525, activation detection circuit520 and/or activation detection component 545 as previously described inconnection with at least FIG. 5.

For example, block diagram 1400 illustrates state machine 1430, whichcan include a parameter register 1436 configured to store one or moreparameters for one or more states of state machine 1430, e.g., aspreviously described in connection with FIG. 12. For example, parametersregister 1436 can store indications of whether each potential state ofstate diagram 1200 is enabled and indications of one or moreconfigurable counter values corresponding to a duration of eachpotential state of state diagram 1200. In some embodiments, one or moreof the parameters of parameters register 1436 can be configured bycontroller 535 before controller 535 enters a sleep or lower power mode.

State machine 1430 can further include a counter 1434 configured tocount continuously during each enabled state until a configurablecounter value is reached. Such a configurable counter value can bedefined by parameter register 1436. Counter 1434 reaching a configurablecounter value can trigger a state change signal 1438 for advancing statemachine 1430 to the next enabled state. Counter 1434 can be configuredto reset based on reaching the configurable counter value for aparticular state and begin counting for the timing of the next enabledstate. As illustrated, counter 1434 can receive a clock signal 1432coordinating such counting. In some embodiments, clock signal 1432 canbe derived from a clock signal of the ADC of the AFE. For example, theADC clock signal can be a 32 kHz clock signal provided by, e.g., ahighly accurate quartz crystal. In some embodiments, this ADC clocksignal can be divided by 32 to obtain clock signal 1432, having afrequency of 1,024 Hz. However, the present disclosure is not so limitedand clock signal 1432 can be obtained and/or generated in any suitablemethod and can have any suitable frequency.

Block diagram 1400 further illustrates a pre-count sample buffer 1404configured to receive and temporarily store one or more current countsamples 1402 generated by the ADC based on a current flowing throughanalyte sensor 530 during pre-count sampling state 1208.

Block diagram 1400 further illustrates a differentiator 1406 configuredto subtract the current count sample stored in precount sample buffer1404 from a subsequently received current count sample 1402 generated bythe ADC based on a current flowing through analyte sensor 530 duringpulse-count sampling state 1220. Differentiator 1406 can output thedifference value to a multiplexor (MUX) 1412. Based on a differentialmode enable signal 1410, MUX 1412 can be configured to either passcurrent count samples 1402 directly from the ADC (e.g., differentialmode enable=0) or pass the calculated difference value fromdifferentiator 1406 (e.g., differential mode enable=1).

Block diagram 1400 further illustrates an accumulator 1414 configured toaccumulate (e.g., integrate or sum) consecutive samples received fromMUX 1412 and output an accumulated, integrated or summed sample to MUX1416. Based on a sum enable signal 1418, MUX 1416 can be configured toeither pass current count samples 1402 directly from MUX 1412 (e.g., sumenable=0) or pass the accumulated, integrated or summed sample fromaccumulator 1414 (e.g., sum enable=1).

Block diagram 1400 further illustrates a sample buffer 1420 (e.g., afirst-in-first-out FIFO buffer) configured to receive and store one ormore samples from MUX 1416. In some embodiments, sample buffer 1420 isconfigured to concurrently store up to 16 samples. However, the presentdisclosure is not so limited and sample buffer 1420 can be configured toconcurrently store any number of samples, according to the particularimplementation. However, in general, the more samples sample buffer 1420is configured to store concurrently, the more power sample buffer 1420would require.

A threshold detection module 1422 can be configured to determine whethera configurable number of consecutive or non-consecutive samples, outputfrom MUX 1416, satisfy a predetermined and/or configurable thresholdvalue. Threshold detection module 1422 can be configured to generate acontroller wake-up signal 1424 based on satisfaction of thepredetermined threshold value by the configurable number of consecutiveor non-consecutive samples. Controller 535 can be configured to wake up,responsive to controller wake-up signal 1424, and further process thesamples stored in sample buffer 1420 and/or transmit or controltransmission of a signal based on such processing. In some embodiments,controller 535 can be configured to reenter the lower power sleep modeupon completion of such processing and/or signal transmission while theabove-described process(es) are repeated.

An example state-by-state operation will now be described in connectionwith FIGS. 13 and 14 wherein all delay states and all sampling states ofstate machine 1430, as previously described in connection with FIG. 12,are enabled. For example, in some embodiments of a storage mode,state-by-state operation, differential mode enable signal 1410 and sumenable signal 1418 can both be set to high, such that MUX 1412 willultimately pass an output of differentiator 1406 and MUX 1416 willultimately pass an output of accumulator 1414.

As illustrated in FIG. 13, state machine 1430 can initially enter firstdelay state 1206. A first potential 1340 (e.g., 0V in “storage” mode,0.6V in “run” mode) is applied to the working electrode of analytesensor 530 during first delay state 1206. INT_enable signal 1330 is lowduring first delay state 1206. Accordingly, the ADC of sensormeasurement circuitry 525 is not integrating and/or accumulating currentcounts corresponding to current flowing through analyte sensor 530during first delay state 1206. Counter 1434 receives clock signal 1432and continuously increments until a configurable absolute value, definedby parameter register 1436, is reached. Upon reaching the configurableabsolute value, counter 1434 and/or another portion of state machine1430 generates state change signal 1438, triggering a change topre-count sampling state 1208 and a reset of counter 1434.

First potential 1340 (e.g., 0V in “storage” mode, 0.6V in “run” mode) ismaintained at the working electrode of analyte sensor 530 for theduration of pre-count sampling state 1208. INT_Enable signal 1330 is setto high, e.g., at 1332, for the duration of pre-count sampling state1208. Accordingly, the ADC of sensor measurement circuitry 525integrates and/or accumulates current counts corresponding to a currentflowing through analyte sensor 530 for the duration of pre-countsampling state 1208.

During pre-count sampling state 1208, counter 1434 receives clock signal1432 and continuously increments until a configurable absolute value,defined by parameter register 1436 and corresponding to a duration ofpre-count sampling state 1208, is reached. Upon reaching theconfigurable absolute value, counter 1434 or another portion of statemachine 1430 generates state change signal 1438, which causes statemachine 1430 to advance to second delay state 1212, sets INT_Enablesignal 1330 to low, which signals the ADC to stop accumulating thecurrent count sample, generates a pulse 1322 in Pre_Count_Ready signal1320, which signals the ADC to output an accumulated current countsample 1402 to pre-count sample buffer 1404, and resets counter 1434.This accumulated current count sample 1402 can signify an averagecurrent flowing through analyte sensor 530 during pre-count samplingstate 1208. While a single-arrow signal line is illustrated, theaccumulated current count sample 1402 can comprise a multi-bit (e.g.,10- or 19-bit) sample value transmitted in parallel from the ADC toprecount sample buffer 1404 via a parallel (e.g., 10- or 19-bit) databus. Unless otherwise stated, all samples passed by other signalpathways in FIG. 14 can be similar multi-bit sample values transmittedin parallel via similar parallel data buses indicated by the signalarrows in FIG. 14.

Continuing with the discussion in relation to FIG. 13, first potential1340 (e.g., 0V in “storage” mode, 0.6V in “run” mode) is maintained atthe working electrode of analyte sensor 530 for the duration of seconddelay state 1212. INT_enable signal 1330 is low during second delaystate 1212, so the ADC of sensor measurement circuitry 525 is notintegrating and/or accumulating current counts corresponding to currentflowing through analyte sensor 530 during second delay state 1212.Counter 1434 receives clock signal 1432 and continuously incrementsuntil a configurable absolute value, defined by parameter register 1436,is reached. Upon reaching the configurable absolute value, counter 1434or another portion of state machine 1430 generates state change signal1438, which triggers a change to third delay state 1216 and a reset ofcounter 1434.

At the onset of third delay state 1216, a second potential 1342 (e.g.,16 mV in “storage” mode, 0.616V in “run” mode) is applied to the workingelectrode of analyte sensor 530 and maintained for the duration of thirddelay state 1216. During at least the rising edge 1344 of secondpotential 1342, a current flowing through analyte sensor 530 will besubstantially dominated by the RC characteristics of analyte sensor 530,which will substantially dampen out during third delay state 1216.INT_enable signal 1330 is low during third delay state 1216, so the ADCof sensor measurement circuitry 525 is not integrating and/oraccumulating current counts corresponding to current flowing throughanalyte sensor 530 during third delay state 1216. Counter 1434 receivesclock signal 1432 and continuously increments until a configurableabsolute value, defined by parameter register 1436, is reached. Uponreaching the configurable absolute value, counter 1434 or anotherportion of state machine 1430 generates state change signal 1438, whichtriggers a change to pulse count state 1220 and a reset of counter 1434.

Second potential 1342 (e.g., 16 mV in “storage” mode, 0.616V in “run”mode) is maintained at the working electrode of analyte sensor 530 forthe duration of pulse count sampling state 1220. INT_Enable signal 1330is set to high for the duration of pulse count sampling state 1220.Accordingly, the ADC of sensor measurement circuitry 525 integratesand/or accumulates current counts corresponding to a current flowingthrough analyte sensor 530 for the duration of pulse count samplingstate 1220.

During pulse count sampling state 1220, counter 1434 receives clocksignal 1432 and continuously increments until a configurable absolutevalue, defined by parameter register 1436, is reached. Upon reaching theconfigurable absolute value, counter 1434 or another portion of statemachine 1430 generates state change signal 1438, which causes statemachine 1430 to advance to fourth delay state 1224, sets INT_Enablesignal 1330 to low, which signals the ADC to stop accumulating thecurrent count sample, generates a pulse 1312 in Pulse_Count_Ready signal1310, which signals the ADC to output an accumulated current countsample 1402 to differentiator 1406, and resets counter 1434. Thisaccumulated current count sample 1402 can signify an average currentflowing through analyte sensor 530 during pulse count sampling state1220.

Differentiator 1406 is configured to subtract the accumulated currentcount sample 1402 stored at the end of pre-count sampling state 1208from the accumulated current count sample 1402 generated at the end ofpulse count sampling state 1220 and output a differential current countsample to MUX 1412. Differentiator 1406 can be configured to set thisdifferential current count sample to zero if the result would otherwisebe a negative number. Since differential mode enable signal 1410 is setto high, MUX 1412 passes the differential current count sample toaccumulator 1414, which stores the differential current count sample.

Second potential 1342 (e.g., 16 mV in “storage” mode, 0.616V in “run”mode) is maintained at the working electrode of analyte sensor 530 forthe duration of fourth delay state 1212. INT_enable signal 1330 is lowduring fourth delay state 1224, so the ADC of sensor measurementcircuitry 525 is not integrating and/or accumulating current countscorresponding to current flowing through analyte sensor 530 duringfourth delay state 1224. Counter 1434 receives clock signal 1432 andcontinuously increments until a configurable absolute value, defined byparameter register 1436, is reached. Upon reaching the configurableabsolute value, counter 1434 or another portion of state machine 1430generates state change signal 1438, which triggers a change to fifthdelay state 1228 and a reset of counter 1434.

At the onset of fifth delay state 1228, one of the first potential 1340(e.g., 0V in “storage” mode, 0.60V in “run” mode), 0V, or anopen-circuit voltage (e.g., a high impedance state) is applied to theworking electrode of analyte sensor 530 and maintained for the durationof fifth delay state 1228. During at least the falling edge 1346 ofsecond potential 1342, a current flowing through analyte sensor 530 maybe substantially dominated by the RC characteristics of analyte sensor530, which will substantially dampen out during fifth delay state 1228.INT_enable signal 1330 is low during fifth delay state 1228, so the ADCof sensor measurement circuitry 525 is not integrating and/oraccumulating current counts corresponding to current flowing throughanalyte sensor 530 during fifth delay state 1228. Counter 1434 receivesclock signal 1432 and continuously increments until a configurableabsolute value, defined by parameter register 1436, is reached. Uponreaching the configurable absolute value, counter 1434 or anotherportion of state machine 1430 generates state change signal 1438, whichtriggers a change back to first delay state 1206 and a reset of counter1434.

In some embodiments, (e.g., for determining an average impedance ofanalyte sensor 530 during a “run” mode in which analyte sensor 530 isalready inserted in the skin of the host), state machine 1430 can beconfigured to cycle through the above-described states (or a subsetthereof) a predetermined number of times (e.g., 125) over apredetermined interval of time (e.g., 10-12 seconds) before MUX 1416 isconfigured to pass an accumulated current count value from accumulator1414 to sample buffer 1420 and/or to threshold detection module 1422 fordetermination of whether controller wakeup signal 1424 is to begenerated to wakeup controller 535. In some such embodiments,accumulator 1414 is configured to integrate the differential currentcount samples passed by MUX 1412 (e.g., accumulator 1414 adds eachsubsequent differential current count sample to a running sum ofdifferential current count samples previously passed by MUX 1412 duringthe integration period).

Once state machine 1430 has cycled through the above-described states(or an enabled subset thereof) the predetermined number of times, andaccumulator 1414 has summed the differential current count samplesgenerated during the predetermined number of cycles, accumulator 1414 isconfigured to pass the summed differential current count value to MUX1416 and, based on Sum Enable signal 1418 being set to high, MUX 1416 isconfigured to pass that summed differential current count value tosample buffer 1420, which stores the summed differential current countvalue.

In some such embodiments, threshold detection module 1422 can beconfigured to generate controller wakeup signal 1424 responsive to MUX1416 passing the summed differential current count value to samplebuffer 1420 and, in some cases also to threshold detection module 1422.In such embodiments, a configurable threshold for generating controllerwakeup signal 1424 would be receipt and/or storage of one summeddifferential current count value by sample buffer 1420. Responsive tocontroller wakeup signal 1424, controller 535 can be configured towakeup and further process the summed differential current count valuestored in sample buffer 1420 (e.g., dividing the summed differentialcurrent count value by a number “N” of differential current counts,thereby calculating an average current count value that can be utilizedto calculate an average impedance of analyte sensor 530 according to anyappropriate or known processing algorithm, e.g., Ohm's Law, etc.).Accordingly, the battery can be further conserved, even during a runmode, by sleeping controller 535 while state machine 1430 determines oneor more current counts and saves one or more of them in sample buffer1420.

In some other embodiments, (e.g., for determining an impedance ofanalyte sensor 530 during a “storage” mode in which analyte sensor 530is not yet inserted in the skin of the host), state machine 1430 can beconfigured such that, for each cycle through the above-described states(or an enabled subset thereof), MUX 1412 passes the differential currentcount sample, generated by differentiator 1406 during pulse countsampling state 1220 as described above, directly to MUX 1416. MUX 1416,responsive to Sum Enable signal 1418 being low, can pass each of thedifferential current count samples to sample buffer 1420, which storesthe differential current count samples. In such embodiments, accumulator1414 may not integrate multiple differential current count samples fromdifferentiator 1406 and may be effectively bypassed.

Moreover, in some such storage mode embodiments, threshold detectionmodule 1422 can be configured to generate controller wakeup signal 1424responsive to a predetermined and/or calibrated number “N” of thedifferential current count samples stored in sample buffer 1420consecutively or non-consecutively satisfying (e.g., being any one ofgreater than, less than or equal to) a predetermined threshold value(e.g., 0x7FF in hexadecimal notation) or a range of predeterminedthreshold values (e.g., within a range of 0x700 and 0x7FF in hexadecimalnotation). Responsive to controller wakeup signal 1424, controller 535can be configured to wakeup and further process one or more of thedifferential current count values stored in sample buffer 1420 (e.g.,determining whether a false wakeup has occurred and/or calculating anaverage impedance of analyte sensor 530 according to any appropriate orknown processing algorithm, e.g., Ohm's Law). In the event that a wakeupresponsive to generation of controller wakeup signal 1424 issubsequently determined to be a false wakeup, controller 535 may causeanalyte sensor system 308 to re-enter “storage” mode and controller 535may then revert to the lower power mode.

In some yet other embodiments, (e.g., during actual continuous glucosemonitoring), state machine 1430 can be configured such that all statesexcept pre-count sampling state 1208 are disabled and pre-count samplebuffer 1404, differentiator 1406 and accumulator 1414 are effectivelybypassed and/or otherwise disabled. In such embodiments, current countsamples from the ADC of the AFE are passed directly to MUX 1412.Differential mode enable signal 1410 and Sum Enable signal 1418 can bothbe set to low. Accordingly, responsive to differential mode enablesignal 1410 being low, MUX 1412 directly passes the current countsamples to MUX 1416 and, responsive to Sum Enable signal 1418 being low,MUX 1416 directly passes the current count samples to sample buffer1420, which stores each of the current count samples.

Moreover, in some such embodiments, threshold detection module 1422 canbe configured to generate controller wakeup signal 1424 responsive to apredetermined number “N” of the current count samples being stored insample buffer 1420. Responsive to controller wakeup signal 1424,controller 535 can be configured to wakeup and further process one ormore of the current count values stored in sample buffer 1420 (e.g.,calculating an analyte concentration value based at least in part on thecurrent count values according to any appropriate or known processingalgorithm).

In addition, the present disclosure also contemplates the disablement ofone or more of states 1206, 1208, 1212, 1216, 1220, 1224, 1228 aspreviously described in connection with FIG. 12. For example, in someembodiments, fifth delay state 1228, which may also be considered an“extended idle” state, may only be enabled when analyte sensor system308 is in an above-described “storage” mode in which analyte sensor 530is not yet disposed in a skin of the host. Such an “extended idle” statemay be utilized to keep a voltage bias across the terminals of analytesensor 530 at 0V or open-circuit to avoid oxidation and/or other sensordamage that would otherwise be caused by a defined, non-zero voltagebias being applied across the terminals of analyte sensor 530.

In some embodiments, one or both of second delay state 1212 and fourthdelay state 1224 may be disabled. For example, one purpose of delays1206, 1212, 1216, 1224 is to suspend current count measuring, sensingand/or accumulating by the ADC of the AFE during time intervalsimmediately following a change in voltage bias applied to the workingelectrode of analyte sensor 530. Because the working electrode potentialis held constant for the duration of each of pre-count sample state 1208and pulse count state 1220, second delay state 1212 and fourth delaystate 1224 may be superfluous in some such implementations.

In some embodiments where the working electrode potential is held at thesame potential, e.g., 0V, in each of pre-count sampling state 1208 andenabled fifth delay state 1228, first delay state 1206 may be disabledif it would otherwise directly follow fifth delay state 1228 (e.g., allinstances of first delay state 1206 except a first instance during asession), since there would be no change in voltage potential at thetransition from fifth delay state 1228 directly to pre-count samplingstate 1208.

In some embodiments where the working electrode potential is held at thesame potential, e.g., 0.6V while taking continuous analyte concentrationmeasurements during an above-described “run” mode, all states exceptpre-count sampling state 1208 can be disabled, since pulse countsampling state 1220 is not enabled and there would be no change involtage potential applied to the working electrode of analyte sensor 530where no transitions from one state to any other state occur. Moreover,where pulse count sampling state 1220 is disabled, differential modeenable signal 1410 may be forced to the low, disabling state, sincewithout pulse count sampling state 1220, differential current countsamples are not generated or utilized.

An example method 1500 for controlling an analyte sensor system isprovided below in connection with FIG. 15. Method 1500 comprises one ormore steps or actions, which may be interchanged with one anotherwithout departing from the scope of the claims. In other words, unless aspecific order of steps or actions is specified, the order and/or use ofspecific steps and/or actions may be modified without departing from thescope of the claims. Method 1500 may correspond at least to the previousdescription in connection with FIGS. 12-14.

Block 1502 includes utilizing a state machine to cause a first voltagepotential to be applied across an analyte sensor during a first samplingstate and cause a second voltage potential to be applied across theanalyte sensor during a second sampling state. For example, aspreviously described in connection with at least FIGS. 12-14, statemachine 1430 can be configured to cause first voltage potential 1340 tobe applied across analyte sensor 530 during first sampling state 1208and cause a second voltage potential 1342 to be applied across analytesensor 530 during second sampling state 1220. As previously described inconnection with at least FIGS. 13 and 14, in a first operating mode(e.g., a “storage” mode during which analyte sensor 530 is not yetinserted into the skin of the host), first voltage potential 1340 can bezero volts and second voltage potential 1342 is greater than firstvoltage potential 1340 by a predetermined amount (e.g., 16 mV). In asecond operating mode (e.g., a “run” mode during which analyte sensor530 is inserted into the skin of the host), first voltage potential 1340can be the same as the voltage potential applied across analyte sensor530 to determine analyte concentrations within the host (e.g., 0.6V) andsecond voltage potential 1432 (e.g., 0.616V) is greater than firstvoltage potential 1430 by the predetermined amount (e.g., 16 mV).

Block 1504 includes utilizing analyte sensor measurement circuitry togenerate a first digital count corresponding to a first current flowingthrough the analyte sensor during the first sampling state based onapplication of the first voltage potential and generate a second digitalcount corresponding to a second current flowing through the analytesensor during the second sampling state based on application of thesecond voltage potential. For example, analyte sensor measurementcircuitry 525 can be configured to generate a first digital count 1402corresponding to a first current flowing through analyte sensor 530during first sampling state 1208 based on application of first voltagepotential 1340 and generate a second digital count 1402 corresponding toa second current flowing through analyte sensor 530 during secondsampling state 1220 based on application of second voltage potential1342 as previously described in connection with at least FIGS. 13 and14.

Block 1506 includes utilizing detection circuitry to determine a firstdifference between the second digital count and the first digital countand generate a controller wake up signal responsive to at least thefirst difference satisfying a threshold value or a range of thresholdvalues. For example, differentiator 1406 can be configured to determinea first difference between the first and second digital counts 1402 andthreshold detection module 1422 can be configured to generate controllerwake up signal 1424 responsive to at least the first differencesatisfying a threshold value as previously described in connection withat least FIGS. 13 and 14.

Block 1508 includes causing a controller to enter a lower power statefor at least a duration of the first sampling state, the second samplingstate and the determination of the first difference, transition from thelower power state to an operational state responsive to the controllerwake up signal and determine an impedance of the analyte sensor based atleast in part on the first difference. For example, as previouslydescribed in connection with at least FIGS. 12-14, controller 535 can beconfigured to enter a lower power state (e.g., a sleep state) whilestate machine 1430 cycles through those of states 1206, 1208, 1212,1216, 1220, 1224, 1228 that are enabled. Controller 535 can further beconfigured to transition from this lower power state to an operationalstate responsive to controller wake up signal 1424. Once woken,controller 535 can determine an impedance of analyte sensor 530 based atleast in part on the difference between a first digital current count1402 corresponding to the current flowing through analyte sensor 530while first voltage potential 1340 is being applied across analytesensor 530 during first sampling state 1208 and a second digital currentcount 1402 corresponding to the current flowing through analyte sensor530 while second voltage potential 1342 is being applied across analytesensor 530 during second sampling state 1220. For example, one or morecounts stored in sample buffer 1420 (see, e.g., FIG. 14) are utilized bycontroller 535, upon wake up, to make such a determination of theimpedance of analyte sensor 530

In some embodiments, method 1500 may further comprise initiatingapplication of first voltage potential 1340 across analyte sensor 530during delay state 1206, which immediately precedes first sample state1208 and suspending generation of digital counts 1402 by analyte sensormeasurement circuitry 525 during delay state 1206, as previouslydescribed in connection with at least FIGS. 13 and 14.

In some embodiments, method 1500 may further comprise initiatingapplication of second voltage potential 1342 across analyte sensor 530during delay state 1216, which immediately precedes second sample state1220 and suspending generation of digital counts 1402 by analyte sensormeasurement circuitry 525 during delay state 1220, as previouslydescribed in connection with at least FIGS. 13 and 14.

In some embodiments, method 1500 may further comprise utilizing statemachine 1430 to cause a zero-voltage potential (e.g., first voltagepotential 1340 or an open-circuit voltage) to be applied across analytesensor 530 during delay state 1228, which follows second sample state1220 and suspending generation of digital counts 1402 by analyte sensormeasurement circuitry 525 during delay state 1228, as previouslydescribed in connection with at least FIGS. 13 and 14.

In some embodiments, method 1500 may further comprise storing the firstdigital count 1402 in pre-count sample buffer 1404 prior to thedifferentiator 1406 determining the difference between the digitalcurrent count 1402 received from the ADC during first sampling state1208 and the digital current count 1402 received from the ADC duringsecond sampling state 1220, as previously described in connection withat least FIGS. 13 and 14.

In some embodiments, method 1500 may further comprise receiving, bydifferentiator 1406, the first digital count 1402 from pre-count samplebuffer 1404, receiving, by differentiator 1406, the second digital count1402 from the ADC, and utilizing differentiator 1406 to determine thedifference between those digital current counts, as previously describedin connection with at least FIGS. 13 and 14.

In some embodiments, method 1500 may further comprise utilizingaccumulator 1414 to generate a sum of the first difference and at leasta second difference between a third digital count 1402 and a fourthdigital count 1402, wherein the third digital count corresponds to athird current flowing through analyte sensor 530 during a subsequentinstance of first sampling state 1208 and wherein the fourth digitalcount corresponds to a fourth current flowing through analyte sensor 530during a subsequent instance of second sampling state 1220, aspreviously described in connection with at least FIGS. 13 and 14.

In some embodiments, method 1500 may further comprise generatingcontroller wake up signal 1424 responsive to at least the sum of thefirst difference and the second difference satisfying the thresholdvalue, as previously described in connection with at least FIGS. 13 and14.

In some embodiments, method 1500 may further comprise utilizingcontroller 535 to define at least one parameter of state machine 1430(e.g., as stored in parameter register 1436) before entering the lowerpower state.

Combinations of Activation Detection Techniques

In some embodiments, for a robust wake-up procedure and to avoid falsewakeups, multiple indicators of analyte sensor 530 implantation can beused to determine that analyte sensor system 308 should exit the lowerpower state. Care should generally be taken, however, to avoid damagingor changing the performance properties of analyte sensor system 308, tomaintain robustness against humidity events that may trigger activationprior to implantation of analyte sensor 530, and to maintain relativelylower power operation, which can be important for battery-operateddevices.

In embodiments, the primary and secondary signals from analyte sensor530 may be used for triggering activation of analyte sensor system 308.For example, a secondary signal generated using analyte sensor 530, suchas impedance, may be monitored and compared to a threshold or othercondition. If the secondary signal meets or satisfies the threshold orother condition, then analyte sensor 530 may be caused to gatherinformation related to a level of an analyte in a host. If the level ofthe analyte in the host meets a second threshold or condition, thenanalyte sensor system 308 can be caused to exit the lower power state.In embodiments in which the potentiostat is always on, such that analytesensor 530 is continuously or regularly caused to gather informationrelated to the level of the analyte in the host, the secondary signalcan be monitored for purposes of activating other circuits andsubsystems of analyte sensor system 308.

In embodiments, the primary signal from analyte sensor 530 (which, asdescribed above, relates to or can be used to calculate a level of ananalyte in the user) may be used in combination with a secondary signalobtained using analyte sensor 530 and/or a signal from a sensor or othercomponent that may be included in or used in conjunction with activationdetection circuit 520 and/or activation detection component 545, inorder to control activation of analyte sensor system 308 and reducefalse wakeups. In embodiments, the primary and secondary signals fromanalyte sensor 530 and/or the secondary signals from a sensor or othercomponent that may be included in or used in conjunction with activationdetection circuit 520 and/or activation detection component 545 may beused for activation purposes, where such analyte sensor 530 and othersignals are monitored at more than one time period (e.g., at the variousdiscrete phases where detectable events may typically occur, from beforeimplantation of analyte sensor 530, implantation, and beyondimplantation). Various of these signals can be measured/characterized atdifferent times in order to provide a more robust activation scheme.

Referring further to FIG. 5 (by way of example), in embodiments, asecondary signal from activation detection component 545 may beindicative of analyte sensor system 308 being removed from its productpackaging, or otherwise indicative of a determination that implantationof analyte sensor 530 and/or deployment of analyte sensor system 308 islikely to occur in the near future, and a secondary signal from analytesensor 530 may be indicative of implantation occurring. For example, asecondary signal from an accelerometer or other component/switch usedfor activation purposes (e.g., as described herein) can be monitored,and when the secondary signal indicates that analyte sensor system 308has been removed from product packaging therefor, or that implantationof analyte sensor 530 has occurred or is likely to occur in the nearfuture, analyte sensor 530 may be used to generate a primary signalrelated to the level of analyte in a host. For example, a primary signalrelated to the level of analyte in a host may be used to determinewhether implantation of analyte sensor 530 has occurred. If the primarysignal related to the level of the analyte in the host meets a thresholdor condition, then analyte sensor system 308 can be caused to exit thelower power state. In embodiments, a secondary signal from anaccelerometer can be monitored and another secondary signal may bemonitored by a temperature sensor, conductivity sensor, capacitivesensor, inductance sensor, voltage sensor, impedance sensor, or anyother sensor capable of determining an electrical, physical, magnetic,or chemical property indicative of implantation of analyte sensor 530into a host.

In embodiments, activation detection circuit 520 may monitor for asecondary signal generated by a bridge-based switch/sensor, a pull tabswitch/sensor, an audio sensor, a proximity sensor, an RFID sensor, amagnetic field based switch/sensor, or any otherswitch/sensor/technique, including those discussed herein, where suchswitches/sensors/components are capable of determining that analytesensor system 308 has been removed from product packaging and/or anapplicator, or that implantation of analyte sensor 530 has occurred oris likely to occur in the near future. For example, a secondary signalmay be generated by electrical contacts of a bridge-based switch/sensorbeing disconnected or connected (e.g., as describe above in connectionwith FIG. 6C), which may indicate that analyte sensor system 308 hasbeen removed from product packaging and/or an applicator. Inembodiments, a pull tab-based switch/sensor may be used to cause analytesensor system 308 to generate a secondary signal for activationpurposes. For example, and as discussed herein, a non-conductivematerial may be placed between spring-loaded electrical contacts. Inresponse to the nonconductive material between the spring-loadedelectrical contacts being removed (with or without direct userintervention), the spring-loaded electrical contacts may be caused toform a physical/electrical connection that may electrically couple thecontacts to one another. A secondary signal may indicate that thespring-loaded electrical contacts have been connected to one another,thus initializing the wakeup.

In embodiments, a proximity sensor may generate a secondary signal ifthe proximity sensor determines that analyte sensor system 308 has beenremoved to a threshold distance from product packaging and/or anapplicator. In embodiments, an audio sensor may generate a secondarysignal if an audio signature is recognized (e.g., by employingtransducers and other audio components), where the audio signature mayindicate that analyte sensor system 308 has been removed from productpackaging and/or applicator, or that implantation of analyte sensor 530has occurred or is likely to occur in the near future. Similarly, asecondary signal may be generated using an RFID sensor, magnetic fieldsensor, or any other sensor capable of determining that analyte sensorsystem 308 has been removed from product packaging and/or an applicator,or that implantation of analyte sensor 530 has occurred or is likely tooccur in the near future.

In embodiments, after a secondary signal is detected using one or moreof activation detection component 545 and activation detection circuit520, where the secondary signal may be indicative of analyte sensorsystem 308 being removed from product packaging and/or an applicator, aprimary signal may be generated using analyte sensor 530, where theprimary signal relates to a level of an analyte in a host. Using thelevel of the analyte in the host and a threshold value or othercondition/characteristic that may be indicative of analyte sensor 530implantation, it may be determined whether or not implantation ofanalyte sensor 530 has likely occurred.

For example, a secondary signal may be generated using a temperature orpressure sensor. If the secondary signal generated by thetemperature/pressure sensor meets a threshold value or condition, thenanalyte sensor system 308 may triggered to exit a lower power state. Inthis example, the threshold condition may be a temperature related tothe average body temperature of a host such that analyte sensor system308 may be caused to check whether the lower power state should beexited based upon the measured temperature or temperature gradient. Inembodiments, a secondary signal may be generated using a capacitancesensor or measurement, where the threshold condition may be related tothe expected measured capacitance associated with analyte sensor 530following implantation into a host. In embodiments, a secondary signalmay be generated using a voltage sensor or measurement, where thethreshold condition may be related to an expected voltage across one ormore electrodes of analyte sensor 530 following implantation into ahost. A secondary signal may be generated using any an electrical,physical, magnetic, or chemical sensor capable of measuring a propertyindicative of implantation of analyte sensor system 308 into a host.

In embodiments, primary and/or one or more secondary signals may be usedfor causing analyte sensor system 308 to exit the lower power state.Using primary and/or one or more secondary signals may increase therobustness of the activation scheme for analyte sensor system 308 byreducing the occurrence of false wakeups. In embodiments, monitoring aprimary signal may be conditioned upon analyte sensor system 308detecting two secondary signals that indicate that analyte sensor system308 has been removed from product packaging and/or an applicator, orthat implantation of analyte sensor 530 has occurred or is likely tooccur in the near future. For example, monitoring a primary signal maybe conditioned on a secondary signal generated using an accelerometerand a secondary signal generated using a bridge-based switch/sensor bothsatisfying certain conditions. After both secondary signals aredetermined to satisfy respective conditions associated with likelyimplantation of analyte sensor 530 or deployment of analyte sensorsystem 308, analyte sensor 530 may then monitor for a primary signal(e.g., relating to an analyte level) to determine that implantation ofanalyte sensor 530 has occurred.

In embodiments, any number of secondary signals may be monitored usingany combination of the various techniques described herein andmonitoring the primary signal may be conditioned upon the secondarysignals satisfying respective conditions. In embodiments, the secondarysignals may be monitored simultaneously or in a staged fashion, wheresubsequent secondary signals are only monitored in response to certainsecondary signals meeting conditions associated therewith. For example,secondary signals may be obtained at any time by any secondaryswitch/sensor/component scheme/technique discussed herein usingactivation detection circuit 520 and/or activation detection component545.

In embodiments, as alluded to above, the secondary signals may bemonitored in a particular order or sequence. For example, activationdetection circuit 520 may initially obtain the secondary signalgenerated using a bridge-based switch/sensor and a determination may bemade as to whether this secondary signal indicates that analyte sensorsystem 308 has been removed from product packaging and/or an applicator.Thereafter, if this bridge-derived secondary signal so indicates,activation detection circuit 520 may obtain a secondary signal generatedusing an accelerometer, and a determination may be made as to whethermovement of analyte sensor system 308 is consistent with that of typicalhuman handling or gait, as discussed herein, or is otherwisecharacteristic of analyte sensor system 308 being deployed. If so, theprimary signal that is generated using analyte sensor 530 can then beobtained and checked for purposes of activating analyte sensor system308 or causing the same to exit a lower power state.

Similarly, other combinations of signals may be used to cause foranalyte sensor system 308 to exit the lower power state. For example, ifa secondary signal related to temperature meets a threshold orcondition, then analyte sensor system 308 may be caused to determinewhether the level of analyte in the host that can be measured usinganalyte sensor 530 satisfies a threshold value or condition. Inembodiments, two or more secondary signals from any of theswitches/sensor/component schemes described herein may be used inconnection with determining whether analyte sensor system 308 should becaused to exit the lower power state. In embodiments, the secondarysignals may be monitored simultaneously or they may be monitored in aparticular or staged order.

FIG. 10 is an operational flow diagram illustrating various exampleoperations of method 1000 that may be performed in accordance withembodiments of the disclosure. In embodiments, method 1000 may be usedfor determining whether a first condition and a second condition aresatisfied before activating analyte sensor system 308 or causing thesame to exit a lower power mode. Operation 1002 involves obtaining anelectrical signal using activation detection circuit 520 and/oractivation detection component 545 (referring to FIG. 5, for example).The electrical signal may indicate whether the first condition issatisfied. For example, the first condition being satisfied may dependon whether a first sensor characteristic from a switch/sensor (e.g.,such as an accelerometer, temperature sensor, or any of the othertechniques that may be implemented using one or more of activationdetection circuit 520 and activation detection component 545) isdetected and/or a threshold condition is met. The electrical signal maybe generated using one or more sensors if the first sensorcharacteristic is detected and/or the threshold condition is met.

As described above, the electrical signal may be generated using one ormore of a detected proximity between analyte sensor system 308 and areference object (e.g., an applicator or packaging for analyte sensorsystem 308); a temperature; an output of an accelerometer; a responsegenerated using wireless signaling transmitted or received by analytesensor system 308; a detected change in air pressure; audio information;a signal generated by analyte sensor system 308 in response to detectingphotons; a conductivity, voltage, impedance, resistance, or capacitance,e.g., as measured between two or more terminals of analyte sensor system308 and/or analyte sensor 530; a mechanical or electromechanical switchlocated on or within a housing of analyte sensor system 308 or thepackaging or applicator thereof; the detection of magnetic field; ameasured strain; or another detectable event/condition as describedherein.

At operation 1004, method 1000 may include activating analytemeasurement device 810 (such as, for example, a potentiostat etc.) inresponse to analyte sensor system 308 obtaining or generating theelectrical signal. For example, a bias voltage may also be appliedacross first and second terminals 828 and 830 of analyte sensor 808 ofcircuit 800 (referencing FIG. 8A by way of example) in response toanalyte sensor system 308 obtaining the electrical signal. At operation1006, method 1000 may include using analyte sensor 808 to gather analyteinformation from the host. For example, measurement device 810 may beused in conjunction with analyte sensor 808 to measure a primary signalthat may be indicative of a level of an analyte in a host.

At operation 1008, method 1000 may include determining whether theprimary signal (e.g., related to analyte information) satisfies a secondcondition or characteristic. For example, the primary signal may satisfya second condition if the primary signal meets a predetermined thresholdor other characteristic (e.g., value, gradient, count condition, etc.).The second condition or characteristic may be satisfied if the primarysignal remains constant above a threshold or changes, over a certaintime period. At operation 1010, if the primary signal satisfies thesecond condition, method 1000 may include analyte sensor system 308exiting the lower power consumption mode.

By way of example, if the first condition is satisfied at operation1002, and the second condition is satisfied at operation 1008, circuit800 may then be used to generate output 836 that can cause activation ofanalyte sensor system 308 into a working or operating mode (or forexample, a triggered state, referencing embodiments in connection withFIG. 9). In the working mode or the like, circuit 800 may continue to beused to gather analyte information, and such information may be storedin storage 515 and/or transmitted using TRX 510 (again, referencing FIG.5 by way of example). If, however, it is determined at operation 1008that the analyte information does not satisfy the second condition,method 1000 may return to operation 1002, and analyte sensor system 308may remain in a lower power consumption mode (or for example, anon-triggered state, referencing embodiments in connection with FIG. 9).In example embodiments, the electrical signal may be obtained and/ormonitored/checked at operation 1002 according to a frequency/timeperiod/interval that is predetermined, programmable, adaptable,variable, and/or configurable or the like.

ADDITIONAL EMBODIMENTS

One of skill in the art will appreciate upon studying the presentdisclosure that various additional embodiments not described explicitlyherein are within the spirit and scope of the present disclosure.

FIG. 11 illustrates example computing module 1100, which may in someinstances include a processor/microprocessor/controller resident on acomputer system (e.g., in connection with server system 334, any of thedisplay devices described herein (e.g., display devices 120, 130, 140,310(a, b, etc.), partner devices 315(a, b, etc.), and/or analyte sensorsystem 8, 308, etc. Computing module 1100 may be used to implementvarious features and/or functionality of embodiments of the systems,devices, apparatuses, and methods disclosed herein. With regard to theabove-described embodiments set forth herein in the context of systems,devices, apparatuses, and methods described with reference to thevarious FIGS. of the present disclosure, including embodiments ofanalyte sensor system 308, display device 310, partner devices 315,server system 334, and components of or used in connection with theforegoing as described and/or contemplated herein, etc., one of skill inthe art will appreciate upon studying the present disclosure theadditional variations and details regarding the functionality of theseembodiments that may be carried out by computing module 1100. In thisconnection, it will also be appreciated by one of skill in the art uponstudying the present disclosure that features and aspects of the variousembodiments (e.g., systems, devices, and/or apparatuses, and the like)described herein may be implemented with respected to other embodiments(e.g., methods, processes, and/or operations, and the like) describedherein without departing from the scope or spirit of the disclosure.

As used herein, the term module may describe a given unit offunctionality that may be performed in accordance with one or moreembodiments of the present application. As used herein, a module may beimplemented utilizing any form of hardware, software, or a combinationthereof. For example, one or more processors, controllers, ASICs, PLAs,PALs, CPLDs, FPGAs, logical components, software routines or othermechanisms may be implemented to make up a module. In exampleimplementations, the various modules described herein may be implementedas discrete modules or the functions and features described may beshared in part or in total among one or more modules. In other words, aswould be apparent to one of ordinary skill in the art after reading thisdescription, the various features and functionality described herein maybe implemented in any given application and may be implemented in one ormore separate or shared modules in various combinations andpermutations. Even though various features or elements of functionalitymay be individually described or claimed as separate modules, one ofordinary skill in the art will understand that these features andfunctionality may be shared among one or more common software andhardware elements, and such description shall not require or imply thatseparate hardware or software components are used to implement suchfeatures or functionality.

Where components or modules of the application are implemented in wholeor in part using software, in one embodiment, these software elementsmay be implemented to operate with a computing or processing modulecapable of carrying out the functionality described with respectthereto. One such example computing module is shown in FIG. 11. Variousembodiments are described in terms of example computing module 1100.After reading this description, it will become apparent to a personskilled in the relevant art how to implement the application using othercomputing modules or architectures.

Referring now to FIG. 11, computing module 1100 may represent, forexample, computing or processing capabilities found within mainframes,supercomputers, workstations or servers; desktop, laptop, notebook, ortablet computers; hand-held computing devices (tablets, PDA's,smartphones, cell phones, palmtops, etc.); other display devices,application-specific devices, or other electronic devices, and the like,depending on the application and/or environment for which computingmodule 1100 is specifically purposed.

Computing module 1100 may include, for example, one or more processors,microprocessors, controllers, control modules, or other processingdevices, such as a processor 1110, and such as may be included incircuitry 1105. Processor 1110 may be implemented using aspecial-purpose processing engine such as, for example, amicroprocessor, controller, or other control logic. In the illustratedexample, processor 1110 is connected to bus 1155 by way of circuitry1105, although any communication medium may be used to facilitateinteraction with other components of computing module 1100 or tocommunicate externally.

Computing module 1100 may also include one or more memory modules,simply referred to herein as main memory 1115. For example, randomaccess memory (RAM) or other dynamic memory may be used for storinginformation and instructions to be executed by processor 1110 orcircuitry 1105. Main memory 1115 may also be used for storing temporaryvariables or other intermediate information during execution ofinstructions to be executed by processor 1110 or circuitry 1105.Computing module 1100 may likewise include a read only memory (ROM) orother static storage device coupled to bus 1155 for storing staticinformation and instructions for processor 1110 or circuitry 1105.

Computing module 1100 may also include one or more various forms ofinformation storage devices 1120, which may include, for example, mediadrive 1130 and storage unit interface 1135. Media drive 1130 may includea drive or other mechanism to support fixed or removable storage media1125. For example, a hard disk drive, a floppy disk drive, a magnetictape drive, an optical disk drive, a CD or DVD drive (R or RW), or otherremovable or fixed media drive may be provided. Accordingly, removablestorage media 1125 may include, for example, a hard disk, a floppy disk,magnetic tape, cartridge, optical disk, a CD or DVD, or other fixed orremovable medium that is read by, written to or accessed by media drive1130. As these examples illustrate, removable storage media 1125 mayinclude a computer usable storage medium having stored therein computersoftware or data.

In alternative embodiments, information storage devices 1120 may includeother similar instrumentalities for allowing computer programs or otherinstructions or data to be loaded into computing module 1100. Suchinstrumentalities may include, for example, fixed or removable storageunit 1140 and storage unit interface 1135. Examples of such removablestorage units 1140 and storage unit interfaces 1135 may include aprogram cartridge and cartridge interface, a removable memory (forexample, a flash memory or other removable memory module) and memoryslot, a PCMCIA slot and card, and other fixed or removable storage units1140 and storage unit interfaces 1135 that allow software and data to betransferred from removable storage unit 1140 to computing module 1100.

Computing module 1100 may also include a communications interface 1150.Communications interface 1150 may be used to allow software and data tobe transferred between computing module 1100 and external devices.Examples of communications interface 1150 include a modem or softmodem,a network interface (such as an Ethernet, network interface card,WiMedia, IEEE 802.XX or other interface), a communications port (such asfor example, a USB port, IR port, RS232 port Bluetooth® interface, orother port), or other communications interface configured to operationwith the communication media described herein. Software and datatransferred via communications interface 1150 may in examples be carriedon signals, which may be electronic, electromagnetic (which includesoptical) or other signals capable of being exchanged by a givencommunications interface 1150. These signals may be provided to/fromcommunications interface 1150 via channel 1145. Channel 1145 may carrysignals and may be implemented using a wired or wireless communicationmedium. Some non-limiting examples of channel 1145 include a phone line,a cellular or other radio link, an RF link, an optical link, a networkinterface, a local or wide area network, and other wired or wirelesscommunications channels.

In this document, the terms “computer program medium” and “computerusable medium” and “computer readable medium”, as well as variationsthereof, are used to generally refer to transitory or non-transitorymedia such as, for example, main memory 1115, storage unit interface1135, removable storage media 1125, and/or channel 1145. These and othervarious forms of computer program media or computer usable/readablemedia may be involved in carrying one or more sequences of one or moreinstructions to a processing device for execution. Such instructionsembodied on the medium, may generally be referred to as “computerprogram code” or a “computer program product” or “instructions” (whichmay be grouped in the form of computer programs or other groupings).When executed, such instructions may enable the computing module 1100,circuitry related thereto, and/or a processor thereof or connectedthereto to perform features or functions of the present disclosure asdiscussed herein (for example, in connection with methods describedabove and/or in the claims), including, for example, when the sameis/are incorporated into a system, apparatus, device and/or the like.

Various embodiments have been described with reference to specificexample features thereof. It will, however, be evident that variousmodifications and changes may be made thereto without departing from thebroader spirit and scope of the various embodiments as set forth in theappended claims. The specification and figures are, accordingly, to beregarded in an illustrative rather than a restrictive sense.

Although described above in terms of various example embodiments andimplementations, it should be understood that the various features,aspects and functionality described in one or more of the individualembodiments are not limited in their applicability to the particularembodiment with which they are described, but instead may be applied,alone or in various combinations, to one or more of the otherembodiments of the present application, whether or not such embodimentsare described and whether or not such features are presented as being apart of a described embodiment. Thus, the breadth and scope of thepresent application should not be limited by any of the above-describedexample embodiments.

Terms and phrases used in the present application, and variationsthereof, unless otherwise expressly stated, should be construed as openended as opposed to limiting. As examples of the foregoing: the term“including” should be read as meaning “including, without limitation” orthe like; the term “example” is used to provide illustrative instancesof the item in discussion, not an exhaustive or limiting list thereof;the terms “a” or “an” should be read as meaning “at least one,” “one ormore” or the like; the term “set” should be read to include one or moreobjects of the type included in the set; and adjectives such as“conventional,” “traditional,” “normal,” “standard,” “known” and termsof similar meaning should not be construed as limiting the itemdescribed to a given time period or to an item available as of a giventime, but instead should be read to encompass conventional, traditional,normal, or standard technologies that may be available or known now orat any time in the future. Similarly, the plural may in some cases berecognized as applicable to the singular and vice versa. Likewise, wherethis document refers to technologies that would be apparent or known toone of ordinary skill in the art, such technologies encompass thoseapparent or known to the skilled artisan now or at any time in thefuture.

The presence of broadening words and phrases such as “one or more,” “atleast,” “but not limited to” or other like phrases in some instancesshall not be read to mean that the narrower case is intended or requiredin instances where such broadening phrases may be absent. The use of theterm “module” does not imply that the components or functionalitydescribed or claimed as part of the module are all configured in acommon package. Indeed, any or all of the various components of amodule, whether control logic, circuitry, or other components, may becombined in a single package or separately maintained and may further bedistributed in multiple groupings or packages or across multiplelocations.

[Additionally, the various embodiments set forth herein are described interms of example block diagrams, flow charts, and other illustrations.As will become apparent to one of ordinary skill in the art afterreading this document, the illustrated embodiments and their variousalternatives may be implemented without confinement to the illustratedexamples. For example, block diagrams and their accompanying descriptionshould not be construed as mandating a particular architecture orconfiguration. Moreover, the operations and sub-operations of variousmethods described herein are not necessarily limited to the orderdescribed or shown in the figures, and one of skill in the art willappreciate, upon studying the present disclosure, variations of theorder of the operations described herein that are within the spirit andscope of the disclosure.

In addition, the operations and sub-operations of methods describedherein may be carried out or implemented, in some cases, by one or moreof the components, elements, devices, modules, circuitry, processors,etc. of systems, apparatuses, devices, environments, and/or computingmodules described herein and referenced in various of FIGS. of thepresent disclosure, as well as one or more sub-components, elements,devices, modules, processors, circuitry, and the like depicted thereinand/or described with respect thereto. In such instances, thedescription of the methods or aspects thereof may refer to acorresponding component, element, etc., but regardless of whether anexplicit reference is made, one of skill in the art will recognize uponstudying the present disclosure when the corresponding component,element, etc. may be used. Further, it will be appreciated that suchreferences do not necessarily limit the described methods to theparticular component, element, etc. referred to. Thus, it will beappreciated by one of skill in the art that aspects and featuresdescribed above in connection with (sub-) components, elements, devices,modules, and circuitry, etc., including variations thereof, may beapplied to the various operations described in connection with methodsdescribed herein, and vice versa, without departing from the scope ofthe present disclosure.

What is claimed is:
 1. A system for controlling activation of analytesensor electronics circuitry, the system comprising: an analyte sensor;a magnetic sensor configured to trigger a signal responsive to detectinga change in proximity of a magnet to the magnetic sensor; and analytesensor electronics circuitry configured to: transition into anoperational state responsive to the signal; and upon transitioning intothe operational state, receive an indication of one or more analyteconcentration values from the analyte sensor.
 2. The system of claim 1,wherein detecting the change in proximity is based on detecting adecrease in magnitude of a magnetic field.
 3. The system of claim 2,wherein detecting the decrease in the magnitude of the magnetic field isbased on the magnetic sensor changing from a first state to a secondstate in response to the magnet being moved away from the magneticsensor.
 4. The system of claim 1, wherein detecting the change inproximity is based on detecting an increase in magnitude of a magneticfield.
 5. The system of claim 4, wherein detecting the increase inmagnitude of the magnetic field is based on the magnetic sensor changingfrom a first state to a second state in response to the magnet beingmoved closer to the magnetic sensor.
 6. The system of claim 1, whereinthe magnet is disposed on a display device configured to display the oneor more analyte concentration values.
 7. The system of claim 1, whereinthe magnet is disposed within a packaging comprising the system.
 8. Thesystem of claim 1, wherein the magnet is disposed within an applicatorof the system.
 9. The system of claim 1, wherein the magnetic sensor isadapted to trigger the signal responsive to the magnet being moved in atleast one of a predetermined motion or a predetermined spatialorientation with respect to the magnetic sensor.
 10. The system of claim1, wherein the analyte sensor is mechanically and electrically coupledto the analyte sensor electronics circuitry prior to implantation of theanalyte sensor into a host.
 11. The system of claim 1, wherein theanalyte sensor electronics circuitry is configured to determine that thesignal is indicative of the system being removed from a packaging of thesystem.
 12. The system of claim 1, wherein the analyte sensorelectronics circuitry is configured to determine that the signal isindicative of implantation of the analyte sensor into a host.
 13. Amethod for controlling activation of analyte sensor electronicscircuitry, the method comprising: detecting a change in proximitybetween a magnet and a magnetic sensor, the analyte sensor electronicscircuitry being electrically coupled to the magnetic sensor; andresponsive to detecting the change in proximity between the magnet andthe magnetic sensor, generating a signal operable to cause the analytesensor electronics circuitry to transition into an operational state.14. The method of claim 13, wherein detecting the change in proximity isbased on detecting a decrease in magnitude of a magnetic field.
 15. Themethod of claim 14, wherein detecting the decrease in the magnitude ofthe magnetic field is based on the magnetic sensor changing from a firststate to a second state in response to the magnet being moved away fromthe magnetic sensor.
 16. The method of claim 13, wherein detecting thechange in proximity is based on detecting an increase in magnitude of amagnetic field.
 17. The method of claim 16, wherein detecting theincrease in magnitude of the magnetic field is based on the magneticsensor changing from a first state to a second state in response to themagnet being moved closer to the magnetic sensor.
 18. The method ofclaim 13, wherein the magnetic sensor is adapted to trigger the signalresponsive to the magnet being moved in at least one of a predeterminedmotion or a predetermined spatial orientation with respect to themagnetic sensor.
 19. The method of claim 13, wherein the signal isindicative of implantation of an analyte sensor into a host.
 20. Themethod of claim 13, wherein the signal is indicative of removal of ananalyte system from packaging of the analyte system.